Less Than Lethal Technology

Less Than Lethal Technology
Less Lethal Technologies
Initial Prioritisation and Evaluation
T Donnelly
Publication No 12/01
POLICE SCIENTIFIC DEVELOPMENT BRANCH
HOME OFFICE POLICING AND CRIME REDUCTION GROUP
PSDB 12/01
i
LESS LETHAL TECHNOLOGIES
INITIAL PRIORITISATION AND EVALUATION
T DONNELLY
FIRST PUBLISHED 2001
© CROWN COPYRIGHT 2001
The text of this publication may not be reproduced, nor may talks or lectures based on
material contained within the document be given, without the written consent of the
Director, Home Office Police Scientific Development Branch.
PSDB No 12/01
Published by:
Home Office
Police Scientific Development Branch
Sandridge, St. Albans
Hertfordshire AL4 9HQ
United Kingdom
Printed by:
White Crescent Press
Crescent Road
Luton
Bedfordshire
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PSDB 12/01
Management Summary
The Home Secretary has tasked the Police Scientific Development Branch (PSDB) of
the Home Office with reviewing available technologies that have the potential for use
as an option that is less lethal than a firearm. This work is being carried out at the
request of the Association of Chief Police Officers (ACPO) and the Northern Ireland
Office (NIO).
In February of this year, PSDB carried out a review of commercially available and
near-market less lethal technologies, which was made available on the NIO website in
April. That report highlighted a wide range of technologies and a large number of
products that could potentially be employed in situations where a less lethal option is
considered appropriate for use. Many of these devices are used operationally in
various countries throughout the world.
Since the report in April, prioritisation of these technologies has taken place based on
evaluations of the technologies and comparison with the Operational Requirements.
The prioritised areas are impact devices, long-range chemical delivery devices, water
cannon, electrical devices that can be used at range, laser/light devices and noise
generating devices. Tranquillisers and malodorants have been selected as requiring
research over a longer period of time while all other technologies have been placed in
the category of not requiring further research at the present time.
The business of policing necessarily involves dealing with people in a wide variety of
situations. These situations will range from one on one confrontations with an
aggressor, who could be armed with any one of a number of weapons, through to the
targeting of individuals within a crowd during serious public disorder. The
Operational Requirements (OR) of the police in terms of less lethal tactical options,
the units deploying these options and the weaponry itself may differ considerably
from one scenario to another.
The purpose of this report is to explain the work that has been carried out in Phase 2
of the project and to demonstrate how devices have been selected for further research
from the large number of technologies considered in the April report. Information is
provided on testing which has been carried out on the various technologies,
information that has been gained, both operational and technical, and the current
status of each of the prioritised areas.
A number of devices have been identified within each prioritised category as meeting
the basic evaluation criteria. Further testing of these devices will now be carried out to
assess how their performance relates to other aspects of the operational requirement.
This will be followed by a full medical review of those devices that appear most
suitable.
It must be stressed that this work is not focussed on identifying a replacement for
conventional firearms since the need to resort to lethal force on occasions will
continue. However, a much broader range of options, which can be considered and
deployed in response to particular circumstances, is required.
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MANAGEMENT SUMMARY……………………………………………………………iii
1
INTRODUCTION…………………………………………………………………………1
2
CATEGORY A TECHNOLOGIES…………………………………………………… 3
3
IMPACT DEVICES……………………………………………………………………. 4
3.1
LASD/Penn State Impact Testing……………………………………………………. 6
3.2
PSDB Testing and Initial Evaluation Criteria………………………………………… 8
3.3
L21A1 Baton Round…………………………………………………………………… 12
3.4
Operational Information…………………………………………………………………13
3.5
Conclusions………………………………………………………………………………13
4
LONG RANGE CHEMICAL DELIVERY DEVICES………………………………… 14
4.1
PSDB Testing and Initial Evaluation Criteria………………………………………… 16
5
WATER CANNON……………………………………………………………………… 16
5.1
Summary of Home Office Work on Water Cannon, 1981-1987…………………… 16
5.2
Current Water Cannon Work…………………………………………………………. 18
5.3
Health and Safety Issues……………………………………………………………… 21
5.4
Operational Issues………………………………………………………………………22
6
ELECTRICAL DEVICES……………………………………………………………… 24
6.1
Tasers…………………………………………………………………………………… 24
6.2
Other Electrical Devices……………………………………………………………… 36
6.3
Considerations For Acceptability………………………………………………………40
6.4
Conclusions………………………………………………………………………………40
7
DISTRACTION / DISORIENTATION DEVICES…………………………………… 41
7.1
Laser/Light Devices…………………………………………………………………… 41
7.2
Noise Generating Devices………………………………………………………………45
8
CATEGORY B TECHNOLOGIES…………………………………………………… 46
8.1
Malodorants………………………………………………………………………………46
8.2
Tranquillisers…………………………………………………………………………… 47
9
CATEGORY C TECHNOLOGIES…………………………………………………… 48
9.1
Stun Grenades………………………………………………………………………… 48
9.2
Smoke…………………………………………………………………………………… 49
9.3
Acoustic Devices…………………………………………………………………………49
9.4
Electromagnetic Waves…………………………………………………………………50
9.5
Nets and Wire Entanglement Systems……………………………………………… 50
9.6
Glue, Foam and Grease……………………………………………………………… 51
10
CONCLUSIONS
iv
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11
ACKNOWLEDGEMENTS…………………………………………………………….. 53
12
REFERENCES………………………………………………………………………… 55
APPENDIX A
SUGGESTED PRIORITIES FOR FURTHER RESEARCH
APPENDIX B
GLOSSARY OF TERMS
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1
INTRODUCTION
"Less lethal" is a term carefully defined to encompass weapons and equipment which,
although less likely than firearms to result in a serious or fatal injury, nevertheless
carry some degree of risk. The objective is to provide the police with options to allow
a use of force commensurate with the threat being faced. This does not preclude the
use of firearms where this is absolutely necessary to protect the public and police
officers. In all cases, the following issues have to be weighed in the balance –
acceptability (including human rights considerations and risk of injury or death),
effectiveness for the purpose, and appropriateness of response.
The business of policing necessarily involves dealing with people in a wide variety of
situations. These situations will range from one on one confrontations with an
aggressor, who could be armed with any one of a number of weapons, through to the
targeting of individuals within a crowd during serious public disorder. The
Operational Requirements (OR) of the police in terms of less lethal tactical options,
the units deploying these options and the weaponry itself may differ considerably
from one scenario to another.
The Home Secretary has tasked the Police Scientific Development Branch of the
Home Office with reviewing the currently available technologies and equipment that
could potentially be employed in situations where a less lethal option is considered
appropriate for use. This work is being carried out as a result of requests from the
following groups:
•
The Home Office Action Against Crime and Disorder Unit (AACDU);
•
The Association of Chief Police Officers (ACPO), specifically the following SubCommittees
- Self Defence Arrest and Restraint (SDAR),
- Police Use of Firearms (PUoF) and
- Public Order;
•
The Northern Ireland Office (NIO), in response to the recommendations made in
the report of the Independent Commission on Policing in Northern Ireland (the
Patten report)1.
These groups are all represented on one steering committee, the Alternatives to Baton
Round Project Board, formed to address two specific recommendations in the Patten
report. Recommendation 69 of the Patten report stated that:
“An immediate and substantial investment should be made in a research programme
to find an acceptable, effective and less potentially lethal alternative to the Plastic
Baton Round (PBR)”.
Recommendation 70 stated that:
“The Police should be equipped with a broader range of public order equipment than
the RUC currently possess, so that a commander has a number of options at his/her
disposal which might reduce reliance on, or defer resort to, the PBR”.
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Early in the life of the NIO project it was recognised that the work being carried out
for the groups mentioned above was essentially the same and that it could be coordinated to suit the policing needs of the whole of the United Kingdom, broadening
out to encompass individual cases. Consequently, representatives from all interested
parties were invited to sit on the project board and a project co-ordinator was
appointed (from ACPO).
The review and assessment of less lethal options is being carried out in a number of
stages, as defined by the board. Four main phases were identified, each involving
separate pieces of work:
Phase 1:
This involves defining the operational objectives against which less lethal
options must be tested; preparing a literature review of available less
lethal options, or those under research and; examining the literature
review against the operational objective.
Phase 2:
This involves evaluating the literature review and formulating proposals
for further research on those options that have the potential for successful
transfer to the operational field.
Phase 3:
This phase involves conducting further research on the options identified
in Phase 2 and will include the evaluation of both performance and safety.
Phase 4:
This phase involves the defining of operational objectives for public order
equipment.
In February 2001, PSDB prepared a report for the NIO which comprised a survey of
technologies and currently available or near market commercial devices, set against
the context of the ACPO operational requirements (Phase 1). This report is available
from the Northern Ireland Office website (www.nio.gov.uk) under the title ‘Patten
Recommendations on Baton Rounds’ and is contained within the document ‘Patten
Report Recommendations 69 and 70 Relating to Public Order Equipment’, dated
April 20012.
In July of this year, and on the basis of information supplied by PSDB, ACPO and the
NIO prioritised the technologies identified in this report in order that research and
testing could be carried out more quickly on those deemed to be most likely to satisfy
the operational requirements. The other technologies could be given longer timescales for completion of the work. This prioritised list split the technologies into three
categories:
•
Category A included ‘devices which may be the subject of immediate more in
depth research’;
•
Category B included ‘devices warranting further research over a more extended
time frame’ and;
•
Category C included ‘devices which presently do not require further research’.
A summarised version of this list is shown in Appendix A.
This report contains a summary of all of the work that has been carried out by PSDB
in relation to less lethal options since the initial review in April2. Information is
provided on testing which has been carried out on the various technologies,
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information that has been gained, both operational and technical, and the current
status of each of the prioritised areas. The purpose of this report is to explain the work
that has been carried out in Phase 2 of the project and to demonstrate how devices
have been selected for further research from the large number of technologies
considered in the April report.
Before any of the less lethal technologies and devices are used by the police in the
UK, it is strongly recommended that they are subject to a full and thorough
evaluation, including an assessment of the medical aspects of using such a device. The
work that has been carried out to date has resulted in a number of devices being
identified as having the greatest potential and meeting the most basic requirements.
These devices must now be subjected to more detailed testing to assess how they meet
other aspects of the requirement, and various devices will almost certainly be
discounted at later stages if they fail to show all of the necessary characteristics.
Those devices that perform well in future tests will be passed to a panel of
independent medical experts for an assessment of the effects that they are likely to
have on the human body. The results of all of the testing that will have been carried
out before this will be provided to the committee in helping them to assess the various
options.
The various abbreviations and technical terms used throughout this report are
explained in the glossary of terms shown at Appendix B.
2
CATEGORY A TECHNOLOGIES
Those technologies selected for Category A, i.e. those devices meriting immediate
further research, are summarised as:
•
•
•
•
•
Impact Devices or Kinetic Energy Rounds
Long Range Chemical Delivery Devices
Water Cannon, both vehicle mounted and portable
Electrical Devices, particularly the taser
Distraction/Disorientation Devices, particularly laser/light devices and noise
generating devices
The methodology used to evaluate the devices within each of the technology areas in
Category A is essentially the same. Initially, information is gathered on all devices
that are available from a wide range of countries. Manufacturers are asked to supply
technical information relating to their product and, if suitable, to submit their products
for evaluation.
Submitted products take part in a progressive sifting process. The testing is carried out
in stages with the quickest, easiest and cheapest tests being carried out first on all
products. This highlights those that clearly do not meet the necessary requirements
and excludes them from further testing. Those products that meet the basic criteria are
put through to the second stage at which point any deficiencies will again be
highlighted. This continues until only those products that have shown the best
performance and most closely meet the operational requirements are subjected to the
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more time consuming and expensive testing, such as the work required for a full
medical evaluation.
Information on the operational use of the various devices in different countries is also
gathered. This information often comes from police forces but may also be gathered
from government agencies, literature and the prison service. This information
provides an insight into the extent of use of each device and an indication of its
effectiveness.
Those devices that meet all of the scientific and technical evaluation criteria will then
be assessed by a medical committee who will comment on their effects on the human
body. This committee will consist of a number of independent medical professionals
who have expertise in the technology or effects being considered.
3
IMPACT DEVICES
There are a large number of manufacturers producing a wide variety of impact
munitions. Many of these rounds may be safe and effective when they strike one part
of the body, but may cause serious injury or even death if they strike a different part.
Many manufacturers, for instance, recommend that the round is not fired at the head,
neck, face or spine. It may be impossible to be sure of avoiding this if the round is
inaccurate, therefore accuracy is one of the more important attributes of these types of
round if unintended injuries are to be minimised.
The performance of these rounds, including their accuracy, varies dramatically
depending on the composition of the round, the weapon from which they are fired,
and the quality of the manufacturing process. Manufacturers’ data can often not be
relied on to provide an accurate assessment of the rounds’ capabilities. It is important,
therefore, that these rounds are tested thoroughly to ensure that they meet both the
manufacturer’s claims and the requirements of the user.
Less lethal impact rounds tend to fall into specific classes. These were outlined in the
April report2 and are summarised below:
•
Bean Bag: A square, rectangular or circular fabric bag containing lead shot. The
round is intended to flatten on impact, hitting face on, and spread its energy over a
large area. These rounds are intended to be fired directly at an individual;
•
Sock Round: A modification of the bean bag, designed to have no edges or
corners which could lead to penetration, and tending to have a ‘tail’ to aid
stabilisation in flight. These rounds are intended to be fired directly at an
individual;
•
Single Flexible Ball Round: This consists of a single ball (generally rubber or
plastic) of various sizes, which may deform on impact to spread the energy over a
larger area. These rounds are intended to be fired directly at an individual;
•
Multi-Ball Rounds: Also known as pellets. A single cartridge can contain from 2
to over 200 pellets, each varying in size from about 0.25 to over 0.75 inch (6–
19mm). These rounds can be fired directly or skip-fired off a hard surface in front
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of the target. They can be used to target a number of people together and are not
as discriminate as many of the other rounds;
•
Fin-Stabilised Rubber Projectile: A single rubber round with a finned tail to aid
stability in flight. These rounds are intended to be fired directly at an individual;
•
Multi-Baton Rounds: These generally consist of 3 or 5 batons in a single
cartridge, generally made from rubber, wood or foam. These rounds can be fired
directly or skip-fired in front of the target. As the batons spread during flight,
these tend not to be as discriminate as other rounds;
•
Single Baton Rounds: This class includes sponge and foam grenades and other
rubber or plastic batons that are present as a single round per cartridge. This class
also includes the current UK baton round, the L21A1, although this has not been
included in this study as extensive testing has already been carried out for this
round. These rounds are intended to be fired directly at an individual;
•
Encapsulated Rounds: These include projectiles that contain a liquid, powder or
other material within a protective coating or shell; upon impact, the contents
should be dispersed. These are dealt with in Section 4, under the heading ‘long
range chemical delivery devices’.
Most of the rounds detailed above are available in a range of calibres, mainly 12
gauge, 37mm and 40mm. There are also a number of rounds available that are fired
from launchers specific to that munition. Figure 1 shows a selection of various impact
munitions.
FIGURE 1:
Various Impact Rounds
It is clear that there are a vast number of less lethal impact rounds available.
Manufacturers also make many versions of each of the different types of munition.
The remaining sections of this chapter provide some information regarding the
performance of these rounds.
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3.1
LASD/Penn State Impact Testing
In February of this year ‘The Attribute-Based Evaluation (ABE) of Less-Than-Lethal,
Extended-Range, Impact Munitions’, prepared by the Los Angeles Sheriff’s
Department (LASD) in conjunction with the Applied Research Laboratory of
Pennsylvania State University, was published3. This report detailed a study in which
80 different types of impact munitions were tested for accuracy. The tests, carried out
in Los Angeles, provided a preliminary evaluation of off-the-shelf less lethal
munitions to allow a side-by-side comparison of different classes of round, different
calibres and different manufacturers’ products.
It is important to note that only 5 rounds of each type were fired in these tests, and the
authors recommended that further tests be conducted using larger sample sizes. The
results do, however, give an indication of the capabilities of the various munition
types. It is also worth noting that the weapons were fired by hand throughout the
study by experienced LASD officers, and the weapon was not clamped. A summary
of the most important points from the study is given below.
Table 1 splits the 80 rounds tested into weapon used and class of munition, using the
previous definitions (the L21A1 baton round was not included in these tests). This
table gives an indication of the range of munitions available and the relative
proportions of each class of munition. It can be seen that, of the rounds tested, 5 used
launchers other than standard weapons.
Class of Munition
12 gauge
10
Bean bag
5
Sock Round
0
Single Flexible Ball
Rounds
6
Multi-Ball Rounds
4
Fin-Stabilised
Rubber Projectile
1
Multi-Baton Rounds
0
Single Baton Rounds
1
Encapsulated
Total
27
TABLE 1:
37mm
4
1
0
37/40mm
3
0
1
40mm
4
0
0
Other
0
0
0
Total
21
6
1
5
2
9
0
5
0
1
0
26
6
1
4
0
17
3
0
0
16
4
2
0
15
0
0
4
5
9
6
5
80
Distribution of Rounds by Class and Calibre
All of the rounds were fired at a target from a distance of 21 feet (6.4m). Table 2
shows the spread (in mm) that was achieved for each class of munition within each
calibre (spread is taken as the maximum distance between two shots in a grouping).
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Class of Munition
Bean bag
12 gauge
65 – 75
37mm
100-305
37/40mm
150 - 290
40mm
100 – 340
Other
-
Sock Round
140 - 790
90
-
-
-
-
-
140
-
-
Single Flexible Ball
Rounds
Multi-Ball Rounds
140 – 790
650 - 1150 405 - 1195 585 - 1170
215
Fin-Stabilised
Rubber Projectile
Multi-Baton Rounds
75 - 255
65 - 125
-
-
-
75
330
915 - 990
380 - 1120
-
Single Baton Rounds
-
90 - 265
-
90 - 230
-
100
-
-
-
90 - 240
Encapsulated
TABLE 2:
Spread of Rounds (in mm) at 21ft (6.4m)
The results at 21ft (6.4m) show that the multi-ball rounds in all standard calibres and
the multi-baton rounds in 37mm and 40mm calibres produce the largest spread, with a
number of types producing a spread of greater than 1m at this range. This is as
expected as these classes of rounds are designed to spread their impact over a larger
area. The variation in spread between different devices within a particular class is also
highlighted, for instance 5 different types of 12 gauge sock round that were tested
produced a spread of 140mm for one type, up to 790mm for a different type of sock
round. The most consistent round at this range was the 12 gauge bean bag, with 10
different types producing a spread from only 65mm to 75mm.
A number of rounds were then fired at a target from a distance of 75 feet (22.9m).
Table 3 shows the spread (in mm) for each class of munition within each calibre. Only
38 of the 80 munitions were tested at this range. The numbers in brackets (n) indicate
the number of each type of munition that was tested within each class.
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Class of Munition
Bean bag
12 gauge
240-915+
(n=10)
165 – 620
(n=5)
-
37mm
380-915+
(n=4)
650
(n=1)
-
NR
NR
Fin-Stabilised
Rubber Projectile
Multi-Baton Rounds
190 – 380
(n=4)
NR
495 – 545
(n=2)
NR
Single Baton Rounds
-
280 – 405
(n=2)
-
Sock Round
Single Flexible Ball
Rounds
Multi-Ball Rounds
Encapsulated
125
(n=1)
37/40mm
530-915+
(n=1)
-
40mm
370-915+
(n=4)
-
Other
-
915+
(n=1)
NR
-
-
NR
NR
-
-
-
NR
NR
-
-
125 – 255
(n=2)
-
-
-
-
915+
(n=1)
KEY:
NR indicates that no results were obtained for this class of munition.
915+ means that the spread was greater than 915mm, the maximum size of impact
plate.
TABLE 3:
Spread of Rounds (in mm) at 75ft (22.9m)
The results at 75ft (22.9m) highlight the inaccuracy of many of the rounds at this
range; a number of rounds did not strike the impact plate, which had a diameter of
915mm. The variation in performance of different rounds within a class is also once
again highlighted, for example 10 types of 12 gauge bean bags showed a variation in
spread of between 240mm for one type of round up to greater than 915mm for another
type.
Two of the observations made by the authors in this report are worth noting:
i)
They were ‘struck by the general inaccuracy of these munitions’;
ii)
They had observed several misfires.
A full copy of this report can be downloaded from the website:
http://www.arl.psu.edu/areas/defensetech/defensetech.html
3.2
PSDB Testing and Initial Evaluation Criteria
The purpose of the PSDB testing programme is to identify those rounds that meet the
necessary requirements. It has already been demonstrated that there is a wide variation
in performance of rounds, both between classes and between individual rounds within
a class. It is necessary, therefore, to verify that the rounds can perform to the agreed
requirements.
The initial evaluation criteria for this type of munition, which have been agreed with
the steering committee, are summarised below:
•
The device should be accurate and suitable for use within the range 1-20m, and
up to 50m if possible;
•
Accuracy is defined as the ability to hit a 400mm wide x 600mm high target:
should achieve a 95% probability of hit with a bench-mounted system and an
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85% probability of hit when fired by an officer dressed in appropriate
patrol/public order dress and equipment, from the standing and kneeling
positions;
•
The device should have a single point of aim;
•
The round should not be of greater energy than that of the L21A1 baton round at
20m;
•
Any platforms for delivery are acceptable other than conventional firearms, for
example a 9mm handgun or an MP5 (note: a 12 bore shotgun is an acceptable
platform);
•
The round is intended to deliver a blunt impact and not to penetrate the outer
skin;
•
The round should consistently strike the target in the manner in which it was
intended.
These initial criteria are likely to be refined further as more is learned about the
capabilities of the various rounds.
3.2.1
Procedure
PSDB have had positive responses from a number of manufacturers producing a range
of impact rounds, interested in submitting products for evaluation. Some of these
manufacturers produce a wide range of different classes of impact munition, of
varying calibres. PSDB are carrying out a number of basic tests on all submitted less
lethal impact munitions. These are designed to measure a number of different
characteristics of the rounds and to address some of the initial evaluation criteria:
•
Accuracy – this is recorded by measuring the spread of the rounds at various
distances (spread is taken as the maximum distance between two shots in a
grouping). The rounds are fired from a suitable weapon that is securely clamped
and mounted. Generally, 10 rounds of each munition are fired at each distance (5,
10, 15 and 20m) for the initial tests.
•
Kinetic Energy (KE) – the velocity (v) of each round is measured at the muzzle
and the target. Using the mass (m) of each round, kinetic energy values can be
calculated for each munition at the muzzle and the target (KE = ½ mv2).
•
Orientation of the round on impact - with the use of a high-speed video
camera, it is possible to record the orientation of the round as it strikes the target.
This is important as, for example, problems have been noted with bean bags that
did not open correctly in flight and struck edge-on, thus leading to a higher
energy density (i.e. energy per unit area) than intended and the possibility of
penetration.
•
Reliability and Consistency - throughout these tests, a general assessment can
be made of reliability and consistency and any problems noted, for example any
misfires or variations in muzzle velocity.
As mentioned previously, the testing of these rounds is carried out in stages. The
initial stage involves the testing of products to determine accuracy, range, velocity,
kinetic energy, orientation on impact, consistency and reliability. In these initial tests,
generally only ten rounds of each type are fired in order to obtain some basic
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information about their performance. Many more rounds would need to be fired to
obtain more statistically significant results and this will be carried out if initial results
are promising.
3.2.2
Results
These results are discussed below using the classes defined earlier.
i)
Bean Bags
A number of bean bags have been tested so far, of rectangular, square and circular
shape. With the square and rectangular rounds, the high speed video camera footage
showed that many of the rounds hit the target edge-on while some were still folded in
half when they struck the target. This leads to a much higher energy density (energy
per unit area) at the target than the intended presentation, i.e. the bag striking face on
with the largest surface area hitting the target. This variation in impact energy affects
both the operational performance of the round and the degree of risk to which a
person is exposed; indeed a number of deaths have been associated with the
penetration of bean bags into the body. This effect has been observed elsewhere and is
one reason why manufacturers have developed the sock round.
As this effect is well known, and has occurred with a number of different rounds
which PSDB have tested, it can reasonably be assumed that the effect is inherent to all
bean bags of this type. This does not meet the part of the initial evaluation criteria for
impact devices which states that “the round should consistently strike the target in the
manner in which it was intended”. For this reason, square and rectangular bean
bags will no longer be included in the PSDB test programme.
Similar initial tests carried out on circular bean bags show that some varieties are not
folded in the cartridge in the same way that the square and rectangular versions are.
This means that they may not be subject to the same problems with orientation as
previously identified with square and rectangular varieties. Further testing of these
types of rounds is required.
ii)
Sock Rounds
The sock rounds that have been tested so far have passed the basic requirements for
accuracy at 20m. In terms of the orientation of the rounds on impact, the high speed
video camera footage showed that, for most of the rounds, the ‘stabilising’ tail was
generally not trailing behind the round as expected but was usually standing straight
up or hanging below the main body of the sock round. It may be that this behaviour
will not cause any undesired effects, and therefore further testing of these rounds will
continue.
iii)
Multi-Ball Rounds
The rounds of this class that have been tested spread quite considerably when fired
and are very inaccurate. This is an inherent property of this class of round as they are
designed to spread their impact over a larger area and may even be used to target a
number of people at one time. This characteristic does not meet with the part of the
initial evaluation criteria for impact devices which states that “the device should be
accurate and suitable for use within the range 1-20m, and up to 50m if possible”. For
this reason, multi-ball rounds will no longer be included in the PSDB test
programme.
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iv)
Multi-Baton Rounds
No multi-baton rounds have so far been submitted to PSDB for testing. These rounds
have the same inherent characteristics as the multi-ball rounds, i.e. they are designed
to spread after firing and impact over a larger area. It is highly unlikely that this class
of round will meet the basic accuracy requirements, however a selection of products
will be tested, if submitted, to verify this.
v)
Fin-Stabilised Rubber Projectile
A number of products of this class have so far been tested at PSDB. The performance
of these rounds varied considerably between individual products, but some have met
the basic requirements for accuracy and orientation on impact at 20m. These rounds
will go through to the second stage of testing which requires more rounds to be fired
to provide statistically significant results. The variation in performance of these
rounds demonstrates the importance of submitting each of the products for testing in
order that the better performing rounds can be identified and separated from those
with poor performance.
vi)
Single Flexible Ball Rounds
All of the rounds within this class that have been submitted have failed to meet the
necessary basic accuracy requirements at 20m and will not go through any further
stages of testing. This could be due to the quality of the submitted products, rather
than an inherent problem with all single flexible ball type rounds, therefore initial
testing will continue on any other products of this class that are submitted.
vii)
Single Baton Rounds
Only one product of this class, apart from the L21A1 which is mentioned in Section
3.3, has so far been found to meet basic requirements for accuracy and orientation on
impact at 20m. This round will therefore go through to the second stage of testing,
which requires more rounds to be fired to provide statistically significant results.
Testing will also continue on any other products of this class that are submitted.
3.2.3
Further Work
It can be seen that a number of products have been identified as meeting the basic
requirements for accuracy and orientation of the round on impact. This is based on ten
rounds of each type fired from a clamped and bench mounted weapon, i.e. under ideal
conditions. These tests are necessary to allow a scientifically accurate comparison
between different types of rounds. The tests are also relatively easy and less time
consuming than others, and can therefore be applied to the volume of rounds received
for initial testing. Further tests are, however, necessary to provide more realistic and
statistically significant results. These will be carried out on those products that have
passed the initial stages of testing.
The types of further tests to be carried out are summarised below:
•
Multiple shots (50) fired from a bench mounted system for each round to ensure
reliability;
•
Testing of rounds at distances greater than 20m;
•
Rounds subjected to extremes of temperature then assessed for performance and
accuracy;
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•
Point of aim/point of impact data obtained for rounds fired at a range of distances
from an appropriate weapon;
•
User handling trials to assess the performance of the weapon system when handfired at stationary and moving targets and under non-ideal conditions;
•
Further multiple shots (hundreds) fired from bench mounted and hand held
systems to obtain statistical values for accuracy;
•
Additional tests as required by the medical committee for assessment.
This series of tests is written in an order which allows the less expensive and time
consuming tests to be carried out first, with rounds being progressively dismissed if
they fail to meet the requirements at any of the stages. For example, if a round fails to
meet the necessary criteria after 50 bench-mounted shots are fired, it will be dismissed
from the testing and will not go through the extreme temperature tests.
3.3
L21A1 Baton Round
Although recommendation 69 of the Patten report called for “an acceptable, effective
and less potentially lethal alternative to the Plastic Baton Round”, the round that is
currently available has been used operationally and a few of its characteristics are
worth mentioning here.
3.3.1
Background
The L21A1 round was introduced in June 2001 following an extensive development
programme. The round is part of a system that includes the L104 37mm baton gun
fitted with a new optical sight. The use of this system will have significant accuracy
advantages over the previously used L5A7 with the L104 fitted with iron sights. The
statement of the independent medical committee4, who reviewed this system,
concluded that the new system (in comparison to the previous system) will, by virtue
of its increased accuracy, reduce the incidence of people other than the targeted
individual being struck directly. This will also reduce the incidence of direct head or
upper thorax impacts and thereby reduce the incidence of life-threatening injuries,
however very serious head injuries will still occur should the round strike the head.
These statements assume that both systems are being used according to the guidelines.
3.3.2
Performance of System
The grouping of rounds is exceptionally good, surpassing anything else tested to date.
At 20m rounds are grouped well within a 300mm circle and extending out to 50m still
fall within the required target area. This is illustrated in Figure 2, which shows a
grouping from a typical proof firing of 30 rounds at 50m. The target size is 250mm
wide x 750mm high and the rounds have fallen within an area of approximately
150mm wide x 350mm high (well within the desired values as detailed in the initial
evaluation criteria, Section 3.2).
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FIGURE 2:
Grouping of L21A1 at 50m
3.4
Operational Information
Impact munitions are a widely used category of less lethal device throughout the
world and different countries often use different types of round. Impact projectiles
were first introduced in the United States for operational purposes in police
departments during the 1960’s. A wide variety of rounds have been used throughout
the various forces with bean bags being the most widely used round and baton rounds
also proving very popular. Encapsulated rounds filled with chemical irritant have also
been used. Some police forces in Canada have also used each of these rounds.
Some Australian police forces also provide their Tactical Operations Units with
twelve gauge bean bag rounds. These have been used operationally but other rounds
are now being researched as the results from the bean bags have been ‘inconclusive’.
Baton rounds were first introduced into Northern Ireland in 1970 and have been
associated with a number of fatalities since that time. More than 125,000 baton rounds
have been fired since they were introduced and this has resulted in 17 fatalities and
618 reported injuries; there have been no fatalities since 1989. There have been a
number of changes made to the baton round since 1970. The L104 weapon was
introduced in 1994 and no fatalities have occurred since this weapon was introduced.
Over seventy L21A1 baton rounds have been fired in Northern Ireland this year. It is
worth noting that this round is only available to the UK military and police and is not
available to any other agencies, although some have expressed an interest in using it.
3.5
Conclusions
The initial testing phase for kinetic energy rounds, involving testing of all submitted
products for accuracy, range, velocity, kinetic energy, orientation on impact,
consistency and reliability, is almost complete. Many rounds are highly inaccurate and
failed to meet even the basic accuracy requirements; these products have been
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dismissed from further stages of testing. Additionally, all square and rectangular bean
bags and multiple ball rounds have been dismissed from further testing due to inherent
problems with the rounds.
A number of products have been identified which meet the basic accuracy and
orientation requirements at 20m. These rounds will be subjected to more detailed
testing (Phase 3 of the project) to assess various other aspects of their performance.
Any rounds failing to meet the necessary criteria in future testing stages will be
dismissed from all subsequent testing.
Those products that pass all stages of testing will be passed to the medical committee
who will assess the effects they are likely to have on the human body.
4
LONG RANGE CHEMICAL DELIVERY DEVICES
The report in April2 highlighted a number of chemical irritants that are available for
use in various countries throughout the world. The most widely used of these are CS
(o-chlorobenzylidene malononitrile), OC (oleoresin capsicum, also known as pepper),
PAVA (pelargonic acid vanillylamide), CN (chloroacetophenone) and CR (Dibenz
(b.f.)-1:4-oxazepine). CS is currently the most widely used chemical incapacitant
within the UK police and the one that will be considered in this section.
CS is a peripheral sensory irritant that works as an incapacitant by producing irritation
of pain receptors in the skin and production of a burning sensation over exposed areas.
Secondary symptoms include involuntary blinking of the eyes, disorientation, running
of the eyes and nose, sneezing and coughing.
The April report also highlighted a number of ways of delivering a quantity of
chemical irritant to a subject. These are summarised below:
•
Grenades and Projectiles – This method is indiscriminate and is used either for
crowd control or to fill a room or vehicle with the irritant. The range of these
devices can vary from 10m up to 300m.
•
Personal Incapacitant Sprays – Hand held CS sprays have been widely used by
police forces in Great Britain since 1996. These sprays are very discriminate and
have a maximum range of 3-4m.
•
Long-Range Discriminating Devices – These devices should be capable of
delivering a quantity of chemical irritant discriminately to one individual at a
range greater than that possible with the hand-held sprays.
It is the long-range discriminating devices which have been selected as a priority for
further research and for which there is the greatest requirement (the other two types of
device are currently available and have been fully evaluated in previous years5,6). This
type of device tends to combine kinetic impact effects with chemical irritant effects to
produce incapacitation of the target. The degree of each effect varies with each system
and is dependent on attributes including the velocity, size, shape and design of the
round as well as the quantity of irritant contained within it.
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This class of round, which has also been described as an encapsulated round, includes
projectiles that contain a liquid, powder or other material within a protective coating
or shell; upon impact, the contents should be dispersed. These rounds may provide
some degree of incapacitation by their direct impact effects, however the material
contained within the round, generally a dye, malodorant or chemical irritant, is also
designed to have an additional effect. A number of impact devices are currently
available, or are being developed, to contain one or more of these materials.
Most of the rounds are available in a range of calibres, such as 12 gauge, 37mm and
40mm. There are also a number of rounds available that are fired from launchers
specific to that munition.
As with the impact devices, a number of initial evaluation criteria have been agreed
with the steering committee and applied to long range chemical delivery devices.
These are shown below (note, these devices can be split into two types: those that are
intended to strike the target directly and; those that are intended to strike the ground in
front of the target):
i)
Subject Specific Rounds:
•
The device should be accurate and suitable for use within the range 1-20m if
possible, and ideally up to 50m;
•
Accuracy is determined by the ability to hit a 400mm wide x 600mm high target:
should achieve a 95% probability of hit with a bench-mounted system and an
85% probability of hit when fired by an officer dressed in appropriate
patrol/public order dress and equipment, from the standing and kneeling
positions;
•
The incapacitant ‘cloud’ must rise to meet the face of the target;
•
The distribution of the incapacitant ‘cloud’ must be greater than the grouping
capacity of the rounds when bench fired at a specific range;
•
Secondary missiles should not cause serious injury;
•
Minimum potential risk from hazardous debris;
•
The round should consistently strike the target in the manner in which it was
intended.
ii) Multiple Subject Incapacitant Rounds:
•
The round should strike a point on the ground within a 1m2 area of the point of
aim;
•
The incapacitant ‘cloud’ must rise to meet the face of the target;
•
The incapacitant ‘cloud’ should be no greater than 3m in diameter;
•
Secondary missiles should not cause serious injury;
•
Minimum potential risk from hazardous debris.
Once again, these initial criteria are likely to be refined further as more is learned
about the various rounds’ capabilities.
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Section 3 highlighted 5 rounds of this class that were included in the Attribute Based
Evaluation3 for accuracy. To summarise these tests:
•
The 12 gauge encapsulated round gave a spread of 100mm at 21ft (6.4m) and
125mm at 75ft (22.9m);
•
The other 4 encapsulated rounds, which used launchers specific to that projectile,
gave a spread of between 90mm and 240mm at 21ft (6.4m);
•
When one of these projectiles was fired at 75ft (22.9m), it gave a spread of
greater than 915mm.
4.1
PSDB Testing and Initial Evaluation Criteria
PSDB are carrying out tests on this class of round to identify those products that meet
the necessary requirements. The submitted products are put through a series of initial
tests very similar to the kinetic energy rounds. These tests are used to assess various
characteristics of the rounds such as accuracy, range, velocity, kinetic energy,
orientation on impact, consistency and reliability. Subsequent testing will also follow
much the same method as that discussed previously for impact munitions.
Only a limited number of products of this class have so far been submitted to PSDB
for testing, despite a large number of manufacturers having been contacted. None of
these products have met the basic accuracy requirements at 20m, nor indeed even at
15m. Further rounds, which appear to have greater potential than those tested, are
currently in development and some will be available soon for testing. One such round,
the Ring Airfoil Projectile, is still in the development stages and will not be available
for initial testing for some time. Efforts are also continuing to identify additional
manufacturers that may be interested in providing their rounds for assessment.
5
WATER CANNON
Water cannon have been selected for further and immediate investigation and work is
proceeding on the investigation of operational issues and technical specifications of
water cannon. Water cannon were considered for use in the UK in the early 1980’s
and the Home Office conducted extensive research into the feasibility of using them at
that time. A summary of this work is given below, along with the reasons why water
cannon were not adopted at that time. This is followed by a summary of the work that
is currently being conducted in relation to water cannon.
5.1
Summary of Home Office Work on Water Cannon, 1981-1987
Following the disturbances during the summer of 1981, the then Home Secretary
authorised the use of plastic baton rounds and CS pyrotechnic irritant devices for use
as a last resort in situations of extreme public disorder. He also initiated an
investigation into the feasibility of water cannon for use in these situations and a large
programme of work was set up to explore this issue.
Members of the Home Office Police Technical Services Division (PTSD) visited
police forces in Belgium, Holland and West Germany in August 1981 to determine
the effectiveness of water cannon for riot control and to examine the type of
equipment used by the police service in these countries. They found that six models of
water cannon were used operationally in the three countries. In most models
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PSDB 12/01
examined, the jets of water did not have the force and range required to keep rioters at
a distance or to disperse a crowd; they achieved little more than making rioters wet.
However it was felt that, even when the jet power was not sufficient to keep back
rioters, the water cannon were still of some use in that they attracted missiles and
hence took some pressure off the police. The use of a large advancing vehicle would
also cause the crowd to retreat and hence ground could be gained.
The prototype MK9 under test in Germany had a higher jet power and was capable of
preventing the approach of rioters closer than about 30m. The tank capacity was also
larger to allow for the higher pump rate. This model was extremely well protected
against attack as it was very high with smooth sides and possessed no hand or foot
holds, making it very difficult to climb onto while moving. This model was the only
one thought capable of driving rioters back and ‘distancing’ them from the police.
PTSD concluded that water cannon are only effective when used in pairs. It was also
noted that no continental studies had been undertaken on the danger of injury to
demonstrators from the use of high-pressure water jets.
Water Cannon had been used in Northern Ireland in the early 1970’s, however
problems were noticed due to poor manoeuvrability, difficulty in obtaining adequate
water supplies, inadequate protection and small capacity. A (medically safe) dye
added to the water was also found to look like blood when seen on the television.
In September 1981, based on the findings from the initial visit, the Home Office
Scientific Research and Development Branch (SRDB, now PSDB) provided a draft
specification for a UK water cannon incorporating all of the best features seen during
the visit. UK manufacturers of fire fighting vehicles were invited to meet the UK
police specification which sought performance equal to, if not better than, the West
German MK9 water cannon.
A committee was set up to develop a prototype water cannon for use in the UK. Two
vehicles were built, compatible operationally but containing different features to allow
comparisons to be made. They were delivered for evaluation in the summer of 1983
and underwent extensive mechanical and road tests. The opinion of the crews working
the machines was taken into consideration during their evaluation. The machines'
capabilities were demonstrated to senior police officers.
The committee made recommendations for further work on various parts of the
machines and advice on operational issues. One of the recommendations made was
that a medical evaluation of the risk of injuries from the use of water cannon should
be carried out before the vehicles were operationally deployed. The lack of medical
information at that time made it impossible for the committee to provide a firm
recommendation about water cannon, although the exercises that had been carried out
indicated that police use of this equipment in situations of public disorder was a viable
proposition.
In 1984, the Chemical Defence Establishment (CDE) at Porton Down provided a
tentative assessment of the hazards of the Home Office water cannon, making
predictions that the HO water cannon had the potential for significant risks of both
primary injury to the trunk and of secondary skeletal injuries.
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To avoid such injuries the then Home Secretary decided that the use of the water
cannon in the ‘spray mode’ (i.e. firing over the heads of rioters) should be evaluated
instead. This method of spraying would reduce the force per unit area and hence
injury potential. The original prototypes were modified to incorporate this; the end of
each monitor (or spray nozzle) was fitted with a mechanical device to ‘spread out’ the
jet over a larger target area. The possible use of additives, namely dye and/or CS was
considered and a system to allow the use of dye or irritant was fitted to each prototype
(dye was ruled out for operational reasons at an early stage).
The spray mode was however found to be ineffective and other inherent drawbacks
with water cannon were identified, such as the quick exhaustion of the water supply;
the need to protect refill sources; their recommended usage in twos and threes; their
lack of manoeuvrability; and their vulnerability to attack.
As a result, the Secretary of State produced a statement in 1987 stating that any
benefits in the deployment of water cannon would be outweighed by their operational
and tactical disadvantages as outlined above and that it was not proposed to add water
cannon to the range of police equipment. Any developments, including the use of
water cannon overseas, would continue to be monitored so that the position could be
reviewed if necessary.
5.2
Current Water Cannon Work
5.2.1
Technical Specifications
A number of international manufacturers have been contacted and asked to provide
technical specifications of their vehicles. To date, a limited number of responses have
been received. A summary of the technical specifications of currently available
vehicle mounted water cannon is provided below.
i)
Vehicle Size
Water cannon tend to be large vehicles, with their size largely determined by the
capacity of the water tanks on board. Length varies between 6 and 9m, height from
3.6 to 4.2m, and width is generally about 2.5m. Their weight ranges from 18,000kg up
to 21,000kg when full. A typical vehicle is shown in Figure 3.
FIGURE 3:
A typical vehicle mounted water cannon
The large size of the vehicles can prevent access to some narrow streets. Some forces
use hoses attached to the sides of their water cannon to allow water to be used in
alleyways and some buildings.
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ii)
Capacity, Flow Rate and Pressure
The capacity of the tank is the most obvious limiting factor in the use of water
cannon. Vehicles tend to hold between 4000 and 9000 litres of water and, at
maximum flow rate and with all jets operating, the total water capacity can be used in
as little as 4 minutes. Flow rates range from 250 to 1200 litres per minute per monitor
and pressure varies between 5 and 25 bar (500-2500kPa).
Firing the cannon in short bursts preserves water and allows assessment of the
effectiveness of the water cannon during operation. Some models of water cannon are
also available with a "pulsed jet" firing system, which allows conservation of the
limited water supply. These vehicles can fire in three different modes:
•
•
•
Short pulse - a single burst of 5-15 litres of water is fired;
Automatic pulse - 40 to 70 pulses per minute;
Continuous Stream - pumping around 900 litres per minute.
Most vehicles have an additional tank to hold either a dye or an irritant additive,
which is mixed with the water stream. The capacity of this tank tends to be between
132 and 190 litres, and more than one tank may be present in a vehicle. The
concentration of dye or irritant in the water stream can usually be varied by controls
within the crew cabin.
iii)
Accuracy
Aiming of the monitors requires practice. Visibility from the crew cabin can be
limited and the cannon operators are usually seated in the rear of the cabin. They rely
on directions from the driver and commander in the front of the cabin to target and
direct the water stream. Visibility is further decreased when the monitors are firing.
With practice the crew should be able to effectively target individuals in a crowd,
although the width of the water stream prevents the water cannon from being a fully
discriminate weapon. Figure 4 shows the cannon being used for practice in a precision
shooting exercise.
FIGURE 4:
iv)
Precision Shooting Exercise
Refilling
If the water tanks are emptied during operational use then refilling will be necessary.
Most of the available vehicles are capable of refilling at water hydrants or from open
water sources such as rivers and lakes. The refilling operation itself may take 10
minutes to complete, with additional time required for setting up refilling equipment.
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Water cannon crews are trained to carry out the refilling procedure. Another option is
to have a second team ready at the refilling point who will connect the hoses and carry
out the refill and clear away equipment, allowing the water cannon to leave and return
to operation more quickly.
v)
Range
The force of the water jet decreases with distance from the vehicle. At close ranges
and high pressures there may be risk of serious primary or secondary injuries, while at
long ranges the water may not be a sufficient deterrent to protesters.
Most manufacturers claim a range of 40-60m for the water jet. As an example, a total
range of 60m may be possible when both monitors are fired together, although at this
range the pressure of the water may be insufficient to push back or hold a protester; it
may, however, act to deter any closer approach. With the same system, a person could
be held at a distance of 40m.
vi)
Armour and Protection
Armour levels vary from vehicle to vehicle. Protective features may include the
following:
•
•
•
•
•
•
•
•
Steel body panels;
Fixed polycarbonate glazing, fitted as standard to most vehicles;
Water spray systems on the vehicle body, windscreens, roof and wheel arches to
protect against petrol bombs;
Pressurised cab to prevent penetration of smoke and gas;
Barbed wire on the top of the vehicle;
Smooth outer panels and the absence of foot/hand holds to prevent protesters from
climbing onto the vehicle;
Run flat tyres;
Protective grille screens on windows.
vii)
Additional Equipment and Requirements
Vehicles may be equipped with video equipment to improve visibility from the cab
and assist in evidence gathering. A public address system may also be used to warn
the crowd of the use of the water jets. Radio equipment for communication between
crew and officers on foot may also be available in some models.
The specialist nature of these vehicles means that dedicated technical support will be
required to provide maintenance and ensure the machines remain in a working
condition. A technical officer is often present as a member of the vehicle crew.
5.2.2
Portable Water Cannon Systems
Portable water cannon offer the obvious advantage over vehicle mounted systems in
that they are much smaller and therefore more manoeuvrable. These types of device
tend to hold the water in a pack which is strapped to the users back, or in a trolley that
can be wheeled along by the operator.
One system, primarily designed as a rapidly deployable fire-fighting tool, consists of a
13 litre water reservoir, a compressed air supply and an impulse gun. The 13 litre tank
is strapped to the back of the operator who then fires the highly pressurised water at
the target area using the impulse gun. The water is discharged as small, high velocity
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PSDB 12/01
‘packets’, which use the minimum amount of water therefore helping to conserve the
supply.
The overall size of the backpack is 360x260x625mm and it weighs 10.3kg when
empty, 23.3kg when full. The impulse gun uses 25 bar compressed air as the power
source. It is 800mm in length and weighs 6.8kg. When the valve opens, the
compressed air forces the water out of the barrel at high velocity within milliseconds;
this is usually accompanied by a loud noise. A choice of three gun barrel sizes is
available filled with one, half or quarter litre charges of water. The maximum shot
range is said to be 16m, with the width of the spray being 3m at a distance of 5m from
the gun.
Trolleys are also available with a capacity of 35 or 50 litres. This unit is assembled on
a wheel base with brackets for the impulse gun, the air cylinder and a 15m coaxial
hose.
This technology has also been incorporated into a small vehicle. The vehicle is
equipped with a 1000 litre water tank and two 12 litre impulse guns. The maximum
range of the water shot is said to be 64m and the operating pressure of the system is
25 bar (2500kPa).
Figure 5 represents a portable water cannon system that is similar to the one
described.
FIGURE 5: Portable Water Cannon
5.3
Health and Safety Issues
It is accepted that water is capable of inflicting serious injury. These injuries may be
classified as primary or secondary injuries. Primary injuries are those resulting from
the distortion of the body wall by the impact of the jet. These injuries are likely to
occur within the first 0.1-0.2 seconds of impact and may include bruising of internal
organs. Secondary injuries occur as a result of the acceleration of the body as a whole
resulting in collision with hard surfaces. These injuries are largely skeletal, such as
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bone fractures. Other injuries could be caused by debris, accelerated by the force of
the water, striking the person.
The effects of high-pressure water on the human body have not been extensively
studied. The internal kinetics of water jets are complicated, the impact of a jet of
water will have a different effect on the human body than a hit from a solid object
with similar kinetic energy and must be considered differently. Different models of
water cannon have different characteristics, such as coherence of water jet, water
pressure, etc. This means that the operational effectiveness and the risk of injury will
vary depending on the model used.
A small number of papers7,8 have been published which describe eye injuries caused
by high-pressure water jets and fire hoses. The fire hose operated at a pressure of 10
bar (1000kPa), which is within the range of pressures attributed to water cannon; the
distance from hose to target was less than 5m.
5.4
Operational Issues
Information is being gathered from police forces with experience of the use of water
cannon in public order situations. Visits have been made to Northern Ireland, Belgium
and Germany to obtain information on their experiences with water cannon. Contacts
have also been made in other countries and communication will continue to allow
more information to be gained.
5.4.1
Northern Ireland
The RUC in Northern Ireland has operated two vehicle mounted water cannon on loan
from Belgian forces for the past three years. In their first year the water cannon were
not deployed, in the second year they were deployed and used twice and in this third
year the cannon have seen extensive use.
The water cannon are currently deployed in pairs with one water cannon used up front
while the other is in reserve behind. The vehicles can change position with one
covering while the other refills, for example. A crew of five people is used to operate
the cannon. The water cannon are effective in dispersing crowds and keeping people
at a distance from the police lines, with an effective distance of approximately 2030m.
The water cannon are thought to fulfil a useful role and are an important resource for
public order policing, although the model currently used is felt to be lacking in a
number of areas. These include the age of the vehicle (affects vehicle maintenance);
the vehicles’ large size, which restricts their movement and deployment and prevents
access to some narrow streets; limited space and visibility within the cab; lack of
sufficient protection from attack and; limited operation before refilling is required.
While some of these factors are inherent to all vehicle mounted water cannon, others
may be improved by using newer models of cannon with different features such as a
pulsed rather than a continuous stream of water. Other features that may be desirable
include the use of camera equipment, both for evidence gathering and in helping to
aim the cannon jets.
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5.4.2
Belgium
The Belgian water cannon are 14 years old and were manufactured to a specification
drafted by the Belgian Gendarmerie. The vehicles cost around £250,000 to £300,000,
although this is dependent on the specification and the number of cannon required.
The Belgians have used the water cannons successfully in many operations since their
introduction, and have not reported any fatalities or injuries connected with their use.
The Belgian Gendarmerie has a total of 24 fully trained crews and 18 water cannon
vehicles. At least 10 of these vehicles are kept operational at any one time, allowing
necessary repairs and servicing to be carried out and to allow for regular crew
training. A crew of 5 people is used to man the water cannon, each of whom
undergoes specific training prior to operational deployment. Vehicles operate as a
single unit, supported by officers on foot.
At maximum flow rate using both jets, the operational time is limited to 4 minutes,
however the operators are trained to use the water sparingly, firing in bursts of 10 to
15 seconds then judging the response before firing again. This preserves the water
supply and allows an assessment of the effectiveness of the water cannon; the
Belgians have not experienced any problems with the capacity of the water cannon.
The length and pressure of the bursts may be gradually increased until the crowd
complies with police instructions. The jets are able to fire water up to 60m when used
simultaneously and to keep a person at a distance of 40m.
The vehicles have a number of features to protect them from attack. They also have a
number of other items of equipment fitted such as: a video monitor and a number of
cameras; a public address system; search lights; a double sound horn coupled with
blue lights; intercom and radio systems to allow communication of the cabin crew
with ground officers, central command and other deployed units. The Belgian water
cannon also have the facility to add chemical irritants or dyes to the water supply,
although these measures have not been used in practice.
5.4.3
Germany
There are 117 water cannon in service across Germany, operated by the 16 regional
police forces. 30 cannon also belong to the federal police. Many of these are older
models but a number are of a newer variety, recently introduced. Each vehicle costs
approximately £300,000.
The vehicles have a crew of four people. A minimum of two vehicles are deployed to
an incident and each will have a unit of nine officers on foot to provide protection. An
extinguishing agent (Expyrol) can be injected into the water jet to fight fires and CN
is also carried as an irritant additive. The water jets can be sprayed up to 60m. The
vehicles have a number of measures to protect them against attack including no foot
holds or hand holds, heavy-duty polycarbonate windows and run-flat tyres.
Water cannon were used in a number of German cities to disperse May Day protesters
this year, and also during March at Dannenberg against nuclear fuel shipment
protests. 30 vehicles were also assembled at the Gorleben rail terminal, the intended
destination of the nuclear waste flasks.
PSDB 12/01
23
A death was reported in Germany relating to water cannon. A person reportedly fell
under the wheels of the vehicle; no injuries resulting directly from use of the water
jets have been reported.
5.4.4
Other Use of Water Cannon
There are four water cannon in the Netherlands, two in Amsterdam, one in Den Haag
and one in Rotterdam. These are all of an older type, although they are now being
replaced by newer models.
France has seven water cannon. Three of the new generation cannon are in Paris, four
older style models are used in other areas.
The Swiss police have recently purchased the same models of water cannon as used in
Germany.
The prison service in England and Wales has one of the portable water cannon
systems available, but has never used it. They consider its primary role to be for use in
hostage situations, although they do not intend it to be fired directly at a person.
Rather, it is intended as a means of distraction by firing against a wall or ceiling and
using the effects of the water and the loud noise.
6
ELECTRICAL DEVICES
This section includes any device that uses the effects of electricity to incapacitate the
target. There are a variety of different devices available but their principle of
operation is the same. They are battery powered and use a low current, high voltage
impulse shock to provide incapacitation. The electrical stimulus delivered by the
device temporarily interferes with the normal electrical signals generated by the
human nervous system. Incapacitation by electrical means appears to offer a virtually
instantaneous method of incapacitation with almost instant recovery, although some
questions remain on delivery methods and on health effects.
6.1
Tasers
Taser devices operate in the following way: a cartridge is attached to the front end of
the weapon, which contains two barbs (the electrodes) each of which is attached to a
coiled length of wire. The barbs are fired and attach themselves to the skin or clothing
of the targeted individual. When the barbs attach themselves to a person, a current can
be sent down the wires and through the person’s body between the two barb points.
Figure 6 shows a selection of models of taser that are currently available.
24
PSDB 12/01
FIGURE 6:
6.1.1
Selection of Currently Available Models of Taser
Taser Properties
There are a few different suppliers of tasers and each of their models differs in some
way. In many respects, the devices made by each of the manufacturers are very
similar as they are essentially designed to do the same thing. The main similarities
between current models of tasers are:
•
The device consists of a cartridge attached to a hand-held battery operated unit.
When fired, it propels a pair of barbed darts attached to two trailing wires at the
subject. Once contact is made, it begins discharging a metered and pulsed current
through the subject’s body resulting in involuntary muscle spasms and severe loss
of motor control.
•
The current maximum range of any model of taser that we know of is 21ft (6.4m),
which is the maximum length of wire in the cartridge. 15ft (4.6m) cartridges are
generally also available.
•
Most companies now provide new higher powered tasers (up to 26W with a
reported pulse energy of 1.4-1.8 Joules) as well as the older 5-7W systems. These
higher powered tasers only came into operational use in 1999. This will affect the
amount of operational information that can be used to predict the likely risks
associated with these devices.
There are also a number of differences between different companies’ products that
may affect the users’ decision as to which one is most suitable. These differences are
summarised below:
•
Some models are single shot only, i.e. only one cartridge can be inserted at any
time, and this must be removed before a new cartridge can be inserted. Other
models allow two cartridges to be inserted together, resulting in an immediate
PSDB 12/01
25
second-shot capability if required (note: with all models of taser, multiple
discharges of electricity can be applied to the subject using the same initial
cartridge, providing both barbs are still suitably attached to the subjects
body/clothing);
•
Some models of taser resemble a handgun (see Figure 6);
•
Models are available using single laser sights that are intended to show where the
top barb will land on the target. Others use dual laser sights, which are intended
to provide a better judgement of distance and dart angulation by showing where
both barbs will land;
•
A data port is available on some models, which can be plugged into a computer,
with the appropriate software, and downloaded to give information on how often
the taser had been used and the time duration of every activation. A remote firing
capability may also be possible. Other models do not have this capability;
•
Probe-like connections are available on some models, which provide a touch stun
capability at distances of up to 3ft (0.91m);
•
Some models can also be used in ‘stun-gun mode’, which does not require the use
of a cartridge. This involves using the electrodes on the taser to touch directly
against the subjects’ body;
•
Some models provide a continuous timed burst of electricity when the trigger is
pulled, although it may be possible to stop this at any time by flicking the safety
switch. Other models require the firer to keep their finger on the trigger for the
entire time that the electricity is required to flow;
•
Some types of cartridge use a rifle primer as the propellant while others use
compressed nitrogen;
•
Different cartridges have different angles of separation between the barbs. This
means that, at a given distance, some barbs will have separated further than others
– this can have implications on the maximum and minimum effective range of the
devices;
•
After being fired, some cartridges will release a large number of small, confettilike pieces of paper with the serial number of that particular cartridge printed on
them. This helps provide evidence of the use of a particular cartridge at a scene.
In 1999, Sgt. Darren Laur of the Victoria Police Department, Canada, published an
‘Independent Evaluation Report of Taser and Air Taser Conducted Energy
Weapons’9. This report is an unbiased assessment and comparison of a number of
models of taser available at that time; it discusses the strengths and weaknesses of
each of the models (a full copy of the report can be found at
http://www.airtaser.com/laur/report.html). It is worth noting, however, that although
only two years old, this report is already out of date as a number of additions have
been made to the available products since its publication.
6.1.2
Taser Operational Issues
A number of important generic points have been learned about tasers that can affect
their use operationally.
26
PSDB 12/01
i)
Batteries
Different models of taser require different types of batteries, usually either lithium,
alkaline or rechargeable are recommended. Different types of batteries have varying
levels of performance in terms of their power, both in use and when stored, and when
used in different climates.
The voltage rating and current delivered vary with different types of battery, so the
output power produced will also vary. This will affect the amount of electricity that is
passed through the target. Higher powered batteries will produce a higher spark rate
compared to lower powered batteries.
The performance of the different types of batteries with continuous use also varies.
For instance, the performance of alkaline batteries declines steadily throughout the
lifetime of the batteries, with the voltage dropping with every use. With rechargeable
batteries, however, the voltage and therefore performance remains essentially constant
until the batteries are almost exhausted, even after multiple use, at which point there
will be a rapid decline in power.
These effects can be observed by firing two of the same models of taser side-by-side,
one powered by alkaline batteries and one by rechargeable batteries. With continuous
cycles, the spark rate of the rechargeable batteries will be maintained whereas with
the alkaline batteries the spark rate will decrease rapidly with continuous cycles. Note:
when the taser is not fired in continuous cycles, this decline in performance will not
be as rapid as the batteries will have had time to recover in between uses.
The performance of different types of batteries also varies in cold conditions. Alkaline
batteries are affected much more by the cold than rechargeable batteries. This will
result in a lower spark rate, and subsequent lower power output, than at room
temperature.
When the spark rate is lower than normal, due to either partly exhausted or cold
batteries, the number of pulses per second reaching the target will be lower. This will
result in muscular contraction/relaxation cycles at the target instead of the overall
complete muscle stiffening required for total muscular control. This effectively means
that tasers operating at lower spark rates are not as likely to lead to incapacitation.
Rechargeable batteries offer a number of advantages over other types of battery,
however they do self-drain at approximately 1% per day. Therefore, if the taser is not
used for a period of time and the batteries are not recharged, there will be a large
reduction in the power. If rechargeable batteries are used, it is extremely important to
remember to recharge them at regular intervals – one manufacturer recommends
doing this every two weeks.
ii)
Effectiveness
John Cover built the first taser prototype in 1970. The name taser was chosen as an
acronym for “Thomas A Swift’s Electrical Rifle”, after the Tom Swift fantasy stories.
At this time, North American law enforcement agencies did not show much interest in
the device and it was sold mainly to the civilian market. In 1976, some American
police departments began successfully using the taser, which led to further interest by
other police departments, and a growth curve within the American law enforcement
PSDB 12/01
27
community has existed ever since. Today, hundreds of police departments in the
United States use taser technology (note: there are approximately 17,000 police forces
in North America). There have been at least 10,000 operational deployments of the
device. Canadian police forces first began using tasers in December 1998, and an
increase in use and sales has also followed there.
Effectiveness ratings for the 5-7W systems have been quoted as between 85% down
to as low as 50%. It was found that focused individuals were able to fight through the
effects of the electricity and could continue with an attack. 26W tasers were
introduced as an alternative to 5-7W systems as they were expected to be more
effective. The lower-powered systems are believed to interfere with the
communication signals within the nervous system of the target, while the new higherpowered tasers are believed to completely override the central nervous system and
directly control the skeletal muscles, causing an uncontrollable contraction of the
muscle tissue. This is said to be close to 100% effective regardless of the pain
tolerance or mental focus of the individual, providing of course that the barbs attach.
Since the introduction of the higher powered tasers, a large number of volunteers have
been subjected to their effects, mainly American and Canadian police officers,
including those who had previously been able to fight through the effects of the
lower-powered versions. The feedback from these volunteers indicates that the higherpowered tasers are indeed more effective, with few people capable of fighting through
the effects. Tests were recently carried out in Canada, using volunteer police officers
armed with firearms loaded with blanks, who were subjected to the effects of a higher
powered taser. The objective of the exercise was to determine whether the officers
were still capable of discharging their firearms. It was found that, often, the officers
were able to voluntarily discharge their firearms while the electricity was passing
through them.
Operationally, there have been a number of cases where individuals have not been
fully incapacitated by the device. Their muscles have contracted while the taser is
active, but they have not fallen to the ground and, as soon as the power is turned off,
they have been able to remove the barbs from themselves and continue with their
attack.
Since the introduction of the higher-powered tasers, there have been a number of
operational uses allowing some initial effectiveness data to be obtained. To
summarise some of this data, of 356 incidents where cartridges were fired, 38 of these
(10.7%) were ineffective in producing the desired effects, i.e. incapacitation. These
figures relate to the same model of taser and are combined from a few different
sources. Significantly, the portion of these figures which came from Canada show an
ineffectiveness rating of 26.0%. This could be due to the cold climate affecting the
batteries as well as the thickness of the clothing worn by the subject.
There are a number of possible reasons for the failure of taser devices. These are
summarised below:
•
28
Clothing – although the electricity can arc across a gap up to a certain distance,
there may be some situations where the thickness of the clothing worn exceeds
this distance. This is particularly so in cold climates where heavy jackets are
worn. Also, if clothes are loose and hanging and the barb(s) penetrate the clothing
PSDB 12/01
only and not the body, then the current flow could be broken when the clothes lift
away from the body;
•
Low battery charge – the issue of batteries has been discussed already and
reasons have been given as to why they are likely to fail. This has been
recognised as a serious issue by the users and trainers in America and Canada and
a number of failures, which had initially been thought to be due to clothing, are
now suspected to have been caused by low battery charge. They have often found
that when an officer first receives their taser they will demonstrate its sparking to
colleagues, usually a number of times. They may also do a ‘spark-test’ before
taking their taser on duty with them to ensure it is working correctly. These
actions combined can seriously affect the performance of the taser when the time
comes to use it operationally;
•
One or both darts miss the target – this could be due to a number of reasons
including: operator error, errors in the sighting system, errors in the cartridge, a
moving target and the target being out of range. Generally speaking, unless both
barbs attach to the target, the circuit will not be completed and the electricity will
not flow through the target;
•
Subject fought through the effects of the electricity – this has been discussed
already and it is recognised that this may still be a possibility even with the new
higher-powered tasers. Reasons for this happening could include the barbs not
being sufficiently separated, or affecting a group of muscles that are not
sufficiently sensitive;
•
Cartridge failure – identified as the cause of failure in some cases;
•
Problem with taser – other than due to cartridge failure or low battery charge,
such as a mechanical or electrical failure in the circuit;
•
Operator error – for example, failure of the operator to hold down the button to
discharge the current.
The path that the electric current will take after the barbs have been fired at a target is
often difficult to predict. Essentially, electricity will flow along the path of least
resistance. Although ideally the full charge would travel along the wire to the first
barb, through the subject’s body, then out through the second barb, this is not always
the case. Contributing factors to the unpredictability include the presence of metal or
other good conductors; the presence of water; highly resistant material at the target;
and arcing across the wires.
All of the figures for effectiveness quoted previously have only included those cases
where a cartridge was actually fired from the taser, however the taser is often also
used to gain compliance in other ways and often the use of the laser sight(s) alone (if
available) will be enough to gain compliance. In other instances, firing the taser
without a cartridge inserted is enough to gain compliance; this allows the subject to
see the effects of the electricity sparking and hear the loud crackling caused by the
electrical discharge across the electrodes (note: this is not possible with all models of
taser). Additionally, some tasers can be used in stun gun mode to provide a touch stun
capability, this method of application is often used in some American and Canadian
forces. Some figures for effectiveness in this mode show that 118 uses out of 552
PSDB 12/01
29
(21.4%) of one model of taser had been a touch-stun application, with a reported
88.1% success rate.
6.1.3
PSDB Testing
A number of tests have been carried out on various models of taser to measure
characteristics such as their accuracy and electrical output. These aspects of
performance are important from both an operational perspective and also in terms of
the effects they will have on the human body.
i)
Accuracy
Tasers can use either a single laser sight that is designed to show where the top barb
will land on the target; a dual laser sight that indicates where both barbs should land,
or no sights at all. While a large separation of the barbs is desirable to provide
maximum incapacitation, it is also important that both barbs will penetrate the target
or at least attach onto their clothing, otherwise the circuit cannot be completed and the
electricity will not flow through the target.
Accuracy tests are therefore carried out to determine the position of the barbs relative
to the laser dot(s), where present, and the separation of the two barbs at different
distances. Initial tests were carried out indoors at room temperature, with no wind
effect and with the taser clamped firmly using a tripod, therefore representing an ideal
situation and the maximum possible accuracy of the devices.
•
Results
The maximum current range of any model of taser that we know of is 21ft (6.4m).
This is the maximum length of the wires within the cartridge and cannot be exceeded.
15ft (4.6m) cartridges are also generally available, these tend to have a wider angle of
separation between the barbs, meaning that the barbs will be further apart at any given
distance than with the 21ft (6.4m) cartridges. The 15ft (4.6m) cartridges may be more
suitable for use at close-quarters in order that sufficient separation of the barbs is
achieved at relatively close range.
Table 4 shows the typical results that can be expected from 21ft (6.4m) cartridges
fired from a single sight taser. Values given are the separation between the top barb
and the point of aim (the laser-sighting dot), and the separation between the top and
bottom barbs. The ranges show the maximum and minimum values for these while the
mean gives the average values at each distance. These results were obtained from at
least ten shots fired at each range from the same model of taser.
Distance from
taser to target
5ft (1.5m)
10ft (3.0m)
15ft (4.6m)
20ft (6.1m)
TABLE 4:
30
Separation between top barb
and laser dot
Range (mm)
Mean (mm)
20 - 55
15 - 135
90 - 140
105 - 410
39
63
109
287
Separation between top barb
and bottom barb
Range (mm)
Mean (mm)
205 - 260
305 - 440
534 - 685
563 - 905
225
378
601
786
Results of Accuracy Tests carried Out at PSDB
PSDB 12/01
These results are represented in Figures 7 to 10. The figures show the position of each
of the barbs at each distance as they would fit on a man-sized target, with the outline
showing torso, leg and arm areas. The point of aim is taken as the centre of the chest
area just above the nipple line (0,0).
Barb displacement relative to aim point (mm)
5 ft from target
100
0
-300
-200
-100
0
100
200
300
-100
Top
Bottom
-200
-300
FIGURE 7:
Position of Taser Barbs at 5ft (1.5m)
Barb displacement relative to aim point (mm)
10 ft from target
300
200
100
0
-500
-300
-100
-100
100
300
500
-200
Top
Bottom
-300
-400
-500
-600
FIGURE 8:
PSDB 12/01
Position of Taser Barbs at 10ft (3.0m)
31
Barb displacement relative to aim point (mm)
15 ft from target
200
0
-800
-600
-400
-200
0
200
400
600
800
Top
Bottom
-200
-400
-600
-800
FIGURE 9:
Position of Taser Barbs at 15ft (4.6m)
Barb displacement relative to aim point
20 ft from target
200
0
-120 -100 -800 -600 -400 -200 0
-200
0
0
200 400 600 800 1000 1200
-400
Top
Bottom
-600
-800
-1000
-1200
FIGURE 10:
ii)
Position of Taser Barbs at 20ft (6.1m)
Electrical Output
PSDB have also carried out tests to determine the electrical output of the tasers in
terms of waveform, current, voltage, pulse-width, energy and power. Measurements
were also made of any changes that occurred to these when an air gap was
incorporated into the circuit (as would be the case if a barb did not penetrate the skin
of the target but instead attached onto their clothing). These tests were necessary not
only to give us a fuller understanding of the taser output, but also to provide
information to an independent medical committee to help them assess the effects of
the taser on the human body. The results provided in this report are not exhaustive and
further analysis of some of the electrical effects is necessary. A more detailed report
32
PSDB 12/01
of this testing will be prepared for the medical committee to provide them with the
information they require.
The electrical signal produced by a taser is very different from the signal produced
from household electricity. Household electrical appliances in the UK have a
continuous alternating current (AC) with a peak voltage of 340V, a root mean square
(rms) voltage of 240V and a frequency of 50Hz (i.e. 50 oscillations per second). This
type of waveform is represented in Figure 11.
FIGURE 11:
Waveform for Household Electricity
Voltage (V)
The taser operates by charging up and then instantaneously discharging a capacitor.
The result is a series of pulses of very high voltage and very short duration. The
pulses last only a few microseconds, while the pulse separations are relatively long in
comparison, lasting tens of milliseconds. Current commercial devices tend to have
between 10 and 30 pulses per second. The high potential difference (or voltage) is
necessary to allow the electricity to jump across an air gap, such as would be the case
if the barbs attached onto a subject’s clothing, rather than penetrating their skin. The
power (wattage) relates to the rate at which the energy is transferred. Figure 12 shows
the typical waveform that is produced from a taser discharge – only one pulse is
represented in this figure.
35000
30000
25000
20000
15000
10000
5000
0
-5000
-10000
-15000
-20000
0
5
10
15
20
25
30
Time (µ
µS)
FIGURE 12:
PSDB 12/01
Typical Waveform for Taser Output
33
Another important distinction between the mains electricity and the output from the
taser is the availability of energy. Each pulse from the taser represents a discrete
package of energy of a more or less constant value, therefore the number of sparks or
packages per second will be the maximum power delivered. Power from the domestic
mains is not limited in this way, the current that can be drawn (which is proportional
to the energy) is not limited to discrete packages and will increase until the load (or
resistance) is met or the fuse or safety device operates.
•
Method
The electrical output of the tasers was measured in the following way: a potential
divider of total resistance Rt was placed across the ends of the barbs, which had been
ejected from the taser cartridges, in order to complete the circuit. The output pulse
from the device was discharged across Rt and the output voltage measured using an
oscilloscope. The total resistance was intended to simulate that of the human body,
but this resistance is highly variable and depends on what part of the body the
electricity is flowing through (tissue, bone, organs, etc.) and also on the individual. A
range of values was therefore chosen for measurement; these values were based on
those previously used in measurements of this type by other agencies10.
Measurements were made of the change of current and voltage with total resistance.
These tests were then repeated with an air gap of a certain distance incorporated into
the circuit. The effects of an air gap on the waveform must be considered if the taser
barbs do not penetrate the skin of a subject, but instead attach onto their clothing. In
this case the electricity can still arc across the gap and be passed through the subject’s
body (depending on the distance of the air gap). In these tests, a gap was created
between one of the barbs and a potential divider of total resistance Rt; the gap was
then increased in 5mm increments. These measurements were repeated using different
values of Rt.
Measurements were also taken of the maximum air gap that could be introduced into
the circuit before the electricity started to arc across the electrodes on the head of the
taser, rather than through the circuit. The limit of the gap was taken as the distance at
which approximately half of the discharges sparked between the two electrodes on the
taser rather than passing through the circuit. These measurements were repeated using
different values of Rt. These measurements were taken as it is important to establish
how the length of the gap will affect the amount of electricity flowing through the
subject. The less electricity that flows through the subject, the less likelihood there is
of incapacitation occurring.
•
Results
In general, the peak output voltage from the tasers increases as the total load
resistance within the circuit increases. When an air gap is incorporated into the circuit
at a set resistance, the waveform changes slightly so that there is a high-voltage, shortduration spike immediately in front of the first main pulse. There is an increase in the
voltage of this spike as the size of the air gap is increased, probably correlating to the
voltage necessary to ionise the air and allow the spark to jump the gap. This large
spike in front of the pulse has a much higher peak voltage than the main pulse,
although it only lasts for a very short period of time. It is as yet unknown what
difference, if any, this will have on the effects of the electricity on the human body.
34
PSDB 12/01
This information, along with all the other electrical output data, will be passed to the
medical committee when they make their assessment.
At resistances of 500 ohms and greater, the maximum air gap that allows only
approximately 50% of the current to flow through the circuit is 20mm (less than an
inch).
iii)
Clothing Penetration
Tests were carried out to determine whether a selection of clothing materials could
prevent the taser barbs from either penetrating through them or attaching on to them.
Taser cartridges were fired at a mannequin dressed in a variety of different clothes of
various materials. In general, most of the materials tested did not stop the barbs from
at least partly penetrating and attaching onto the material. When a number of thick
layers were present together, for example the overlapping section of a leather jacket,
then the barbs would have difficulty in penetrating all of the layers. The zip area was
also a problem as the barbs could not penetrate or attach onto this. Most thin or single
layer materials did not present any problem in terms of barb penetration.
iv)
Flammability
Tests were carried out to determine the risk of ignition if a taser is fired at a person
with flammable liquid on their clothing. The liquid used in these tests was methyl
isobutyl ketone (MIBK), the solvent present in the CS sprays used by the UK police.
A full canister of one model of CS spray, containing MIBK only (30ml) was sprayed
at a mannequin wearing a standard jogging sweatshirt (material is 65% polyester, 35%
cotton). The mannequin was first covered in foil to allow conduction of the electricity
through the barbs. The entire canister was sprayed at the front of the sweatshirt. A
taser cartridge was then fired at the mannequin from a distance of 5ft (1.5m). This was
repeated a total of seven times with a new, but otherwise identical, sweatshirt used
each time.
In five of the occasions, there was no ignition at the mannequin, although sparking
was observed at the barbs attached to the mannequin, indicating that electricity was
flowing through the circuit. On the other two occasions, however, ignition occurred at
the mannequin after the barbs penetrated the sweatshirt. On one occasion the
sweatshirt ignited as soon as the barbs attached to it, and on the other occasion a
second or two passed before the flames began. In both cases, the flames produced
were severe and engulfed the entire top half of the mannequin, including the head.
It is clear from these tests that there is a serious risk of ignition if the taser is fired at a
target that has a flammable solvent on their clothing. This risk will extend to all
flammable environments, for instance a petrol station.
v)
Other Tests
Tests were also carried out to determine how the various models of taser could
withstand treatment such as exposure to extremes of temperature (-10OC to +40OC)
and dropping onto a hard surface. These tests are important as they represent the types
of treatment that the device is likely to be subjected to in the real world when used by
police officers. The performance of the system after it had been subjected to these
conditions was then assessed. Various parts of the system could be affected, such as
PSDB 12/01
35
the batteries, the laser sights, the cartridges and the taser itself and the impact on each
of these areas was measured.
Previous tests had highlighted that the electricity can sometimes arc across the wires
at various points along the circuit, and tended to happen when the resistance of the
target was very high. Tests were therefore carried out to determine at what load
resistance the electricity starts to arc across the wires. This assesses the quality of the
insulation of the wires and is important from an operational perspective since, the
more electricity that is arcing between the wires, the less that is flowing through the
target.
6.1.4
Future Tests
The initial tests have looked at aspects such as accuracy, electrical output, penetration
characteristics, flammability and performance under extreme conditions. These
characteristics affect both the operational and health and safety aspects of tasers.
Further tests to be conducted will include handling trials. This will involve the handfiring of a variety of taser models by police officers at both stationary and moving
targets, including in non-ideal conditions such as low or artificial lighting.
On completion of all of the testing, including the electrical output testing, the results
will be passed to the medical committee for assessment. They will then suggest any
further testing that is necessary before they can provide a full and accurate
assessment.
6.2
Other Electrical Devices
Although most recent interest in the UK has been in the taser devices, it is worth
detailing the other types of electrical devices that are available (note: performance
data has not been verified).
6.2.1
Stun Guns
Many people may be familiar with the concept and appearance of stun guns. They are
hand-held units generally ranging in size from 100-220mm in length and weighing
between 200 and 300g, including the batteries. The probes or electrodes that deliver
the electricity are permanently connected to the unit. These probes are not generally
designed to penetrate the skin of the target, but are intended to be held close up to the
body to allow the flow of charge.
There are a large number of commercially available hand-held stun guns. Some
versions are available which contain extras such as pepper spray or a flashlight as part
of the device. Alternatively, a high intensity flash of light or loud noise may be
emitted when the device is activated. In some cases, optional screw-on lengthening
bars are available to increase the range of the devices; these also increase the distance
between the two probes allowing a greater number of muscle groups to be affected.
Other than in these cases, close contact is required for operation of these devices, as
the probes must be held close to the subject’s skin for effect.
The devices available range in output from 40,000V to 625,000V. Unlike tasers,
which have a large separation of the two barbs, stun guns generally have only 2-3
inches (51-76mm) between the probes. This will result in less muscle groups being
affected by the electricity, making placement of the probes more important. Also,
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unlike the tasers, the stun gun does not attach the probes to the subject’s body, with
the result that close contact must be maintained to prevent the subject voluntarily or
involuntarily ‘jumping’ out of the way of the probes.
Stun guns have been widely used by American law enforcement since the 1970’s.
Many forces also reportedly use the taser without a cartridge to act as a stun gun.
Stun guns have not been selected as a priority for further research within the current
less lethal weaponry programme.
6.2.2
Stun Batons
Stun batons are like standard police batons with an added electrical component. The
batons generally have probes attached to the front end; when the probes are touched
against a person, the trigger is pulled to deliver a shock. Some versions also have
metal bands running part-way along or up the entire length of the baton. In these
cases, if a person grabs the baton along its length, they will receive a shock.
Stun batons are available in ‘one-length only’ and in telescopic/retractable styles with
lengths generally ranging from 300mm to 700mm. Some versions are also available
that contain pepper spray or a flashlight as part of the device. The output from the
batons ranges from 50,000V to 500,000V.
Stun batons have not been selected as a priority for further research within the current
less lethal weaponry programme.
6.2.3
Electrified Riot Shields
Riot shields are also available which have a stun capability. These polycarbonate
shields with electrical contacts fitted to the edges or surface can be supplied as a unit
or alternatively, the electronic package can be modified to mount on other types of
non-conductive riot shields.
Electrified riot shields have not been selected as a priority for further research within
the current less lethal weaponry programme.
6.2.4
Electrified Nets
One company has produced an electrified net that combines entanglement and
electricity to provide temporary incapacitation. When triggered, a large net is
deployed which falls over the subject causing some degree of temporary
incapacitation via entanglement. A pair of long, continuous electrodes is woven into
the net and is attached to a high voltage discharge circuit. These electrodes fall
randomly on the subject’s body, contacting either the skin or clothing. A high-voltage
stunning pulse is then delivered remotely; the net employs a 60,000V electrical pulse
at 25-second intervals for up to 30 minutes to keep the subject subdued. The net has a
claimed range of up to 30ft (9.1m).
Electrified nets have not been selected as a priority for further research within the
current less lethal weaponry programme.
6.2.5
Sticky Shocker
The Sticky Shocker was designed to extend the range for electrically stunning a
person. It is a combination of an impact device and an electrical device. The Sticky
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Shocker is a wireless, self-contained 37/40mm projectile fired from compressed gas
or conventional 37/40mm less lethal weapon launchers. It sticks to the target with a
glue-like substance or with short clothing-attachment barbs; a combination
barb/adhesive attachment head is also available. The projectile incorporates a battery
pack and associated electronics that impart a short burst of high-voltage pulses said to
be capable of penetrating several layers of clothing. The pulse characteristics of the
device are said to be similar to commercial stun guns, with an output of nearly
50,000V.
At present, accurate range is claimed to be 10m although it may be possible to
increase this by reducing the weight and/or increasing the speed of the device. A
remote control option for application of a secondary pulse series and longer-range
units may be developed at a later stage.
In 1999, the NIJ funded a health assessment of the Sticky Shocker. The conclusion
from this was that little information and data currently existed on the health risks of
electrical devices. Further work has therefore been commissioned by the NIJ to assess
the health effects of the Sticky Shocker and other electrical devices. If the Sticky
Shocker is found to be safe, field trials will be conducted thereafter.
6.2.6
Electronic Devices for Security Applications
There are currently a number of unmanned or remotely controlled electronic devices
available for security applications; essentially a less lethal alternative to the AntiPersonnel Landmine. These devices use taser technology for perimeter control by
causing incapacitation of personnel attempting to enter/exit a protected area. One
particular company produces three separate devices of this type. All use cartridges
similar to those used on tasers, i.e. two wires with barbs on the end. One device
contains multiple, independent taser cartridges (15–30ft, 4.6-9.1m) that, when
activated by a sensor, can simultaneously incapacitate a number of subjects. A
modified version of this device allows the remote firing of the cartridges from a
security station rather than the automatic firing when the device’s sensors are tripped.
Each unit will simultaneously launch seven or more independent pairs of darts over an
arc of 120 degrees and out to a distance of up to 30ft (9.1m). The lower dart would
propel out horizontally, hitting at a height of approximately 1.5–2.5ft (457-762mm) at
a distance of 25ft (7.62m). The upper dart would reach a height of 5ft (1.5m) at
maximum range. A timing circuit on the unit, which allows periodic, one second
breaks, is designed to keep the subject(s) incapacitated until security personnel can
attend to them, or until the batteries are depleted.
The third device of this type by the same company is intended to protect key facilities
and a number of the devices would be attached to the outside of the building or
facility, or could be used to cover internal corridors and access doorways. The device
is a permanently installed, armoured, motorised unit incorporating a gun-sighted
video camera and the previously mentioned unit, modified to remotely fire one
cartridge at a time. The remote operator, located in a security room, can rotate the unit
to accurately aim at subjects within 30ft of the device. Once a cartridge is fired, it
remains activated until manually deactivated by the operator.
These devices have not been selected as a priority for further research within the
current less lethal weaponry programme.
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6.2.7
A3P3
The A3P3 (A3: Aerosol Arresting Agent, P3: Pulse Projected Plume) has been
reported in Police magazine. The device is intended to incapacitate an attacker
without excessive force by discharging a highly controlled and debilitating plume of
incapacitant over a range of between one and twenty feet (0.3-6.1m). An ‘on board’
computer determines distance from the subject and makes a choice on spray pattern,
discharge rate and concentration. The device is also fitted with a data recorder (video
and sound) for assessment of potential threat and, presumably, later enquiry into user
action. Developers also envisage that if the device is fitted with a ‘dual stream
configuration’ the liquid discharged can be used to conduct and transfer a high
voltage/low amperage electric charge to the individual. It is suggested that this will
improve the effectiveness of the incapacitant by making the subject inhale in a natural
response to the electric shock. This product is still very much in the development
stages and a fully built device is not yet ready for evaluation.
6.2.8
Electrified Water Cannon
One company has developed a means of delivering an electric shock via water
cannon. A single stream of high pressure, electrified, conductive fluid is emitted from
a gun at high velocity making contact with the target. The high-voltage, low current
pulse that is delivered is said to be capable of delivering a shock even through thick
protective clothing. The water stream can be moved among targets until the selected
target is positively engaged before the high voltage is applied; this avoids stunning
innocent bystanders (or hostages). Ranges of up to 20ft (6.1m) have been
demonstrated with this system (by the manufacturers) but ranges of up to 100ft
(30.5m) or more are claimed to be feasible with improved nozzles and fluids.
The technology can also be used in conjunction with a vehicle-mounted water cannon
for use in crowd or riot control. Longer ranges and longer run times are likely to be
achieved in the vehicle-mounted configuration. The manufacturers have demonstrated
this product in both the hand-held and vehicle-mounted configurations at distances of
up to 20ft (6.1m) although no testing has as yet been performed on live targets.
6.2.9
Stun Belts
Stun Belts consist of a ‘sleeve’ or a band containing the stun power pack that is placed
on the arm or leg of an individual. A remote control transmitter/receiver is used to
activate the device when necessary at distances of up to 200-300ft (61.0-91.4m) away.
The hand-held transmitter sends a signal to the battery-operated receiver located in the
sleeve that activates the stun pack. Stun Belts are intended for use during the
transportation and/or containment of potentially violent individuals. The wearing of
the device in itself may also act as a psychological deterrent against violent behaviour.
Amnesty International has raised some particular concerns about stun belts. They
believe that the belt should be banned because, even when not activated, it is
inherently cruel, inhuman and degrading. The reasons they give for this is that ‘the
fear of infliction of severe pain, in a setting of total powerlessness, constitutes mental
suffering and cruel, inhuman or degrading treatment or punishment’. They have
therefore called for a ban on the manufacture, promotion, transfer and use of the stun
belt and not just a suspension of its use as they have for other electrical devices.
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Stun belts have not been selected as a priority for further research within the current
less lethal weaponry programme.
6.2.10 Telescopic Electronic Restraint Staff
This device is essentially similar to a stun gun; i.e. it has two non-penetrating probes
at the end of it that are touched to a subject’s body to allow incapacitation. The
difference is that this device is 2ft (0.6m) long and can be extended to either 4ft
(1.2m) or 8ft (2.4m), using an extendable telescopic pole. This allows a greater
standoff distance to be achieved.
This device has not been selected as a priority for further research within the current
less lethal weaponry programme.
6.3
Considerations For Acceptability
While it is beyond the scope of this report to provide details on acceptability of
various technologies, it is prudent to mention a number of issues that may need to be
borne in mind if electrical devices are being seriously considered for use in the UK.
Amnesty International is one organisation that has often expressed concerns about
electrical devices (termed ‘electro-shock weapons’ by them). They do not believe that
sufficient health and safety data are currently available with regards to the effects of
this type of electricity on the human body. They have asked that ‘the stun belt should
be immediately banned and the use of other electro-shock weapons such as stun guns,
stun shields, and tasers should be suspended pending the outcome of a rigorous,
independent and impartial inquiry into the use and effects of the equipment’.
As regards relevant health and safety information, it is worth noting the conclusion of
a health assessment on the Sticky Shocker, funded by the National Institute of Justice
(NIJ) in 1999. This review, carried out by a body of independent experts, concluded
that little information and data exist on the health risks of electrical devices (note,
this relates to electrical devices in general although the review was intended to look at
the Sticky Shocker only). Further work has therefore been commissioned by the NIJ
to assess the health effects of the Sticky Shocker and other electrical devices. This
work, some of which uses live pigs to provide data, is due for completion in 2002.
6.4
Conclusions
It has been agreed that only those electrical devices that can be used at range will be
considered a priority for further research. Devices such as stun guns, stun batons and
electrified shields will therefore not be put forward for further testing at present.
Electrified nets and stun belts have also been dismissed as a priority. The taser is
probably the best known and widely available (and used) of electrical devices that can
be operated at range.
A number of limitations in the operational use of tasers have been identified. These
mainly relate to the maximum range of the devices and problems with getting both
barbs to attach on to the target. For this reason, particular interest will be shown to
any developments that allow a greater range to be achieved and/or use other methods
to deliver the electricity to the target.
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Tests carried out on tasers so far have included accuracy, electrical output, clothing
penetration, flammability and performance under extreme conditions. These tests
relate to both operational performance of the tasers and their effects on the human
body. Police handling trials will shortly be conducted to assess the relative merits and
disadvantages of various models of taser.
All of the information gathered will shortly be passed to an independent medical
committee, who are likely to suggest further tests that they consider necessary before
providing an assessment of the effects of this type of device on the human body.
7
DISTRACTION / DISORIENTATION DEVICES
A number of diversion and distraction devices that could be classed as less lethal
weapons were highlighted in the April report2. These devices tended to use the
method of overloading the senses by sound, light, smell or a combination of these to
produce a distracting or disorienting effect. Laser and light devices and noise
generating devices have been selected for further immediate research.
7.1
Laser/Light Devices
Laser and light devices can be used to cause:
•
•
•
•
Aversion response (turn away)
Psychological impact (e.g. fear, confusion)
Hesitation/distraction
Disorientation and reduction in functional effectiveness (possibly leading to
indirect injuries)
Generally, these devices do not incapacitate a person, although there may be some
deterrent effect as the target becomes aware that he/she has been picked out. The
effects of bright light/laser devices can range from dazzle or glare (lasting seconds) to
image formation (after-image lasting seconds to minutes), flashblindness (lasting
seconds to minutes, with after-images lasting from minutes to days) and irreversible
damage. Strobe lights may cause temporary incapacitation. A device that dazzles at
large distances may cause irreversible damage at close range. These devices are also
considerably less effective in daylight or in the presence of strong artificial light
(range reduced by at least a factor of 10).
7.1.1
Lasers
It is claimed that the effective range for laser light may exceed 500m (at night) and
can provide an effective ‘optical shield’ even in daylight. However, laser light
intensity may be severely reduced by smoke and dust.
Blinking and turning away (aversion) is a natural reflex and offers some protection
against low-power, long-pulsed lasers but not high-rate, short pulses which cause
damage after very brief exposures (nanoseconds) and at very low energies
(microjoules).
In general, the eye is most sensitive to 555nm (yellow-green light). Therefore lasers at
this wavelength should achieve the same perceived brightness at lower powers than
more common red lasers.
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At least two devices have been developed for law enforcement applications. One uses
red light (650nm) with an optional strobe and has been certified according to
international standards as being inoffensive to the eye. The device is similar to a
conventional police torch in size and form and is battery powered with a maximum
continuous use time of 20 minutes to avoid overheating. The second device uses green
light (532nm at 140mW) with a built in strobe effect to add to the distraction effect.
The device is about 13 inches (330mm) long, weighs 2.1lbs (953g) and is designed to
look and be operated like a conventional police torch. The device needs to be
recharged after an hour of operation and costs between £3,000 and £6,000 each
depending on quantity ordered.
The power rating of laser distraction devices is relatively high at 100-500mW
compared to less than 5mW in a common laser pointer. The energy received by the
eye remains low as the beam produced by the device has a diameter of up to 2 feet,
spreading the total energy across a wide area.
7.1.2
Lights
Light devices have a shorter range and are less easily focused than lasers. Possible
light devices include high intensity lights and flash discharge units as well as more
conventional flashlights and strobe lights. New LED technology may also lead to high
intensity light devices requiring less battery power. At short range a high intensity
flashlight may be as effective as a laser and is potentially less harmful.
There are many light devices available, the two most common types are:
•
Flashlights - These typically have light outputs from approximately 20,000300,000 candela and are 6-9 inches (152–229mm) long, weighing 7-12 ounces
(198-340g).
•
Portable floodlights - These typically have a light output of 750,000-6,000,000
candela and have dimensions of around 12 inches (305mm) long by 6-15 inches
(152–381mm) high and a weight from 3-25 pounds (1.4–11.3kg). Some require
external power sources.
7.1.3
Laser Hazards
Laser and bright light eye injuries are extensively documented. Injuries are almost
always retinal, ranging from lesions through intraocular haemorrhage to nerve fibre
damage and loss of sight. Treatment for injuries is limited. If pupils are dilated (e.g. at
night) or the eyes are more heavily pigmented, there is greater absorption of energy
and therefore more damage. The effects of coloured laser light on people who are
colour-blind must be considered as some reports suggest they may be less sensitive to
laser light. The impact of strobe lights in triggering epileptic fits has been widely
publicised.
Lasers have been used for many years in various disciplines, including the medical
world, and as such there are several British standards that already deal with laser
safety issues. In the British Standard EN 60825-1:1994, Clause 13 deals with
‘Maximum Permissible Exposure (MPE)’. This is defined as:
“That level of laser radiation to which, under normal circumstances, persons may be
exposed without suffering adverse affects. The MPE levels represent the maximum
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level to which the eye or skin can be exposed without consequential injury
immediately or after a long time and are related to the wavelength of the radiation, the
pulse duration or exposure time, the tissue at risk and, for visible and near infrared
radiation in the range 400nm to 1400nm, the size of the retinal image.”
The MPE at the cornea for ocular exposure to laser radiation, and the same to skin, is
summarised in the standard.
It is widely known that lasers present a hazard to the eye but the skin is also
vulnerable. However, injuries caused to the skin by lasers are less likely to be
permanent, especially at comparatively low energies and so hazards to the eye will be
concentrated upon here.
The British Standard mentioned above considers several determining factors on which
damage to tissue can depend, the first of these being wavelength. The shorter the
wavelength of the radiation, the higher the power. The width of the beam, however,
may spread the power over a wider region, so the power per unit area is also
important. The mechanism of injury is generally accepted to be thermal when the
exposure is of around 0.1s to 10s for a continuous wave laser or arc lamp, or of
around 1 to 10ms when the exposure is from a long pulsed laser or flashlamp. Injury
appears to result from protein denaturation and enzyme deactivation so the variation
of temperature with time must be considered. This is where the size of the beam can
be important again as heat can be conducted away by surrounding tissue far more
efficiently for image sizes of 10µm-50µm than for 1mm. So, although a smaller spot
has a higher power density (power per unit area), this has to be balanced against the
benefits of a smaller spot size in heat conduction. For example, 10W/cm2 for a 1mm
image is the threshold for injury whereas 1kW/cm2 is required in a 20µm image.
Wavelength is also a factor in the site of the tissue injury. Figure 13 shows the types
of injury that can be inflicted at different wavelengths. Some of these injuries may
heal (the cornea completely regenerates every 48 hours), some may be operable
(cataracts) and some are permanent (severe retinal burns leading to blindness).
Visible light and infrared radiation is focussed sharply on to the retina, directly on to
the fovea - the area with the greatest concentration of cone photoreceptors (see Figure
14). This can cause a blind spot in the irradiated area. Outside the fovea it would be
in peripheral vision and not particularly noticeable but inside a severe visual handicap
could occur. At a more detailed level, green lasers are absorbed by the surface layer
of the retina causing abnormal blood vessel growth in front of the photoreceptors
whereas yellow lasers penetrate to damage the photoreceptors directly.
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Radiation Type
UV-C
Wavelength/nm 100
UV-B
280
315
Photokeratitis
•
UV-A VISIBLE IR-A
400
760
1400
Retinal Burns
Cataract →
IR-B
IR-C
3000
106
Corneal Burns
Cataract
ADVERSE
EFFECTS
Colour Vision
Erythema
Night Vision
DEGRADATION
Thermal Skin Burns
Figure 13:
Dependency of tissue effects on the wavelength of the incident
radiation
The retina is also sensitive to the near ultraviolet region but the lens is a strong
absorber of wavelengths shorter than 400nm down to 315nm while the cornea absorbs
heavily at wavelengths below 300nm. It must also be considered that if a laser has
any wavelengths that are outside the human visible range there will be no aversion
response. Therefore, damage can be caused even when the subject is unaware that
they are being exposed.
The British Standard also considers pulse duration and exposure time. The latter is
self-explanatory, energy delivered (and thus injury suffered) increasing with time.
Pulses are often created by so called “Q-switching”. This is a kind of electronic
switch that allows very short, high powered pulses of light to be emitted. It is
significant in that the length of the pulse is often much shorter than the time it takes to
blink or look away so bodily defence against the light is ineffective.
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FIGURE 14:
7.1.4
Composition of the Eye
PSDB Evaluation
PSDB are gathering information on all of the laser and light systems that are available
and have the potential for use in a policing role. The characteristics of these devices
will be assessed, such as power output, wavelength, size of the beam, etc. This data
will then be compared to existing standards. The performance characteristics of the
various devices can then be compared to the operational requirements, and the most
suitable system(s) identified.
7.2
Noise Generating Devices
Audible sound may be used in a variety of ways using soothing, unpleasant or very
loud sounds (up to 135dB) in an attempt to pacify a crowd or clear an area. Devices
may range from whistles and hand-held sirens to large vehicle mounted speakers.
Studies have shown anti-social behaviour decreasing in areas where soothing music is
played. In one example classical music was successfully used to prevent graffiti in
problem areas.
Effects of various noise levels are shown below11:
Discomfort
Threshold of pain
Eardrum rupture
Lung damage
Lethality
120dB
145dB
185dB
200dB
220dB
As a comparison, a busy office typically has a sound level of 65dB, heavy traffic
90dB and a jet aircraft taking off 125dB.
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The Health and Safety Executive have defined acceptable sound levels at work to be
equivalent to no more than 85dB for 8 hours, or a peak level of 140dB regardless of
frequency or duration. Hearing protection must be provided for workers exposed to
sound at higher levels.
High volume (above 150dB), low frequency (50-100Hz) audible sounds are reported
to cause ‘intolerable coughing and choking respiration’ with ‘unpleasant but tolerable
respiratory effects’ at lower volumes and frequencies (20-50Hz)12.
Standard stun grenades use a bright flash of light, a loud bang and intense blast waves
to disorient and/or incapacitate the target(s) (see Section 9.1). Some of these devices
fragment on impact, which could be hazardous to persons in the immediate area
depending on the composition of the grenade. The pyrotechnics used to create the
flash can also be hazardous as they may set fire to combustible materials, such as
paper or fabrics. In addition to this, blast injuries can be caused by discharge when in
contact with or in very close proximity to an individual. The requirement now is for a
non-fragmenting and non-pyrotechnic device that creates a loud noise, sufficient to
disorient and/or incapacitate a target, with no risk of injury from blast effects.
PSDB are gathering information on all available noise generating devices of this type.
Measurements will be made of the peak noise level and sound exposure level of any
device that appears suitable. The performance characteristics of the various devices
can then be compared to the operational requirements, and the most suitable system(s)
identified.
8
CATEGORY B TECHNOLOGIES
Within the second category of prioritisation, as described in the introduction of this
report, two types of technologies have been identified as meriting further research,
although the current state of knowledge and/or the commercial availability of
workable devices has meant that this will necessarily occur over a longer timescale.
These technologies are malodorants and tranquillisers, a description of each is
provided below.
8.1
Malodorants
A malodorant is an extremely bad-smelling compound, traditional stink bombs being
an example of this. Malodorants may be of assistance in dispersing crowds although
they are unlikely to prevent a determined assailant at short range. The possibility of
developing malodorous devices has not been fully explored. Very little has been
published on possible devices.
The US army has proposed that any malodorant used should be perceived highly
unpleasant by most people, quickly detected and dispersed, not easily habituated and
not incapacitating or a sensory irritant.
Studies found odours named ‘Bathroom malodour’ and ‘Who me?’ most repellent,
with transient symptoms of nausea and gagging, but other odours such as cortyl
mercapton (Skunk Perfume) have also been promoted. Recently ‘rotting flesh’ was
felt too repulsive for use with an exhibit at the Natural History Museum in London.
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There are a number of companies specialising in creating chemical smells and
flavours for the food and perfume industries that may be capable of developing
suitable odours in addition to those already on the market.
Means of independently delivering these smells could include similar methods to
those used for delivering CS, dyes, or stun grenades, for example in spray form or
within an encapsulated round. Some manufacturers offer malodorants as an additional
component within other devices (see Section 4).
The above mentioned studies13 reported reduction in respiratory volume, an increase
in respiratory rate, change in the electric resistance of the skin and other symptoms
consistent with tachygastria (nausea). The degree of these responses will be
determined by the concentration of the odour.
The possible effects on people suffering from respiratory illnesses should be
considered and the toxicity of the chemicals used must be established. There may also
be issues about decontamination following deployment, especially in residential or
heavily populated areas.
8.2
Tranquillisers
Strictly speaking, tranquillisers will not produce sleepiness or unconsciousness so, in
the context of using a drug to incapacitate a person, anaesthetic may be a better term
to describe these drugs. However, for the purpose of this update ‘tranquilliser’ will be
used as a generic term to describe drugs that can be used to incapacitate or calm a
person.
Tranquillisers and delivery methods were investigated in the late 1980’s and early
1990’s in the US. One class of tranquilliser was identified as having a large safety
margin between the onset of unconsciousness and death as well as possessing rapid
antidotes. However, the substance also caused muscle relaxation and consequently
could cause a person’s breathing to stop. The typical delay between delivery and
effect was about 30 seconds but could be less if the target was agitated and the drug
was circulated round the body more quickly.
The work was stopped because of perceived liability issues surrounding the injection
of drugs without consent. There was also concern that the type of offender the system
was likely to be used on would possibly be under the effect of some other sort of drug,
either legal, illegal or prescription, and unpredictable effects may occur.
The Department of Health have also been consulted and although they say they could
not comment without specific details of the type of drug being considered they did say
that the idea of using tranquillisers was fraught with the difficulties identified by the
Americans.
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9
CATEGORY C TECHNOLOGIES
As set out in the categories of prioritisation, described in the introduction of this
report, these technologies have been chosen as not requiring further research at the
present time, although further consideration may be given to some of the devices at
some point in the future.
9.1
Stun Grenades
These are also referred to as concussion grenades, distraction devices or flash-bang
devices. These devices aim to disorient and/or incapacitate the target(s), usually by
causing flashblindness (lasting seconds) and temporary deafness (lasting minutes)
along with the disorienting effects of intense blast waves. The devices are
indiscriminate, affecting anybody within range.
Stun grenades are available in a range of forms and sizes depending on the
application. Typically, smaller grenades have impact up to 10m from the centre of the
detonation, with light intensity of 2 million candela and sound levels of up to 175dB
at 2m. More powerful grenades are available with light intensity of up to 8 million
candela and sound levels of 185dB at 2.5m (note: sound levels are discussed in
Section 7.2). These larger devices are designed for use only outdoors or for large
indoor areas (e.g. a warehouse).
The body of the grenade may be metal, cardboard or rubber. Rubber and cardboardbodied grenades split or fragment relatively harmlessly on impact, although they
sometimes contain sub-munitions that can fragment when discharged. The
pyrotechnics employed to create the flash may set fire to paper, fabrics and other
combustibles.
Grenades may be hand thrown, fired from a launcher (delivery ranges quoted up to
130m) or slid under a door. Multiple munitions, smoke, chemical irritants (e.g. CS),
rubber stingballs and/or malodorants may also be incorporated, extending the area and
effectiveness of the device.
There may be injuries to sight or hearing, especially for people close to the centre of
the detonation. With metal-bodied grenades there is a danger of metal fragments
causing shrapnel injuries. Blast injuries may be caused from discharge in contact with
or very close to a person. Where grenades also contain other ingredients, such as
multiple munitions or CS, additional caution must be used in their deployment.
Officers entering an area immediately after detonation require protective equipment
dependent on the grenade type used.
Stun grenades have been successfully employed to return order in US prison riots as
well as in a number of hostage situations. They have been used against street
protestors and rioters, primarily as a means of dissipating crowds. Stun grenades have
also been used in the UK in dynamic entry situations and some injuries have been
reported by officers, both in use and in training. Manufacturers have been addressing
these issues and a limited number of devices reach the ACPO requirements.
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9.2
Smoke
The primary use of smoke is to obscure the vision of the target(s). However, this also
obscures the vision of police officers and may provide a screen to hide people/actions
from the police. Similarly, smoke may be used to screen police movements. The
smoke, once deployed, is unpredictable and may be affected by weather conditions.
In general, smoke devices have similar deployment characteristics to chemical gas
devices or stun grenades. Ideally the smoke should be non-toxic and have no
chemical/biological effect on the target (these will not incapacitate the target).
However, some commercially available devices do contain toxic chemicals.
The smoke grenade is an indiscriminate device and cannot be targeted at individuals.
There may be issues surrounding decontamination of an area and the fire risk of these
pyrotechnic devices. In addition, the possible effects of repeated exposure on the
police must be assessed.
Some medical studies have been carried out on types of ‘smoke’ used in military and
fire service training. These show that some long-term toxicity effects are possible
dependent on exposure and chemical content of the smoke.
The possibility of ill effects on people with respiratory problems (e.g. asthma), or
secondary injuries caused by panic and obscured vision, resulting from use of such
devices must be considered.
9.3
Acoustic Devices
Acoustic devices can be sub-divided into three categories:
•
•
•
Infrasound (less than 20Hz), below the threshold of hearing
Audible (20Hz-20kHz) (dealt with in Section 7.2)
Acoustic shock wave devices
Some reports claim physical effects from sound at distances up to 100m. However, as
directionality and attenuation (the way in which volume decreases with distance) are
frequency dependent, the reported effectiveness and directionality of sound devices
are challenged – suggesting a maximum range of a few tens of meters14. Other than
whistles and compressed air-horns and stun-grenades, current devices are generally
large and unwieldy (semi-portable or vehicle mounted).
9.3.1
Infrasound devices
There has been much speculation about the effectiveness of infrasound devices.
Frequencies of 19Hz have been reported to cause the subject to observe apparitions in
enclosed spaces. Violent nausea has been reported at 12Hz and lower frequencies of
3-7Hz are reported to cause death by resonance with internal organs15. The lowest
frequencies (less than 3Hz) are claimed to enhance relaxation and drowsiness or
sexual excitation. However, when exposed to infrasound not everybody experiences
the same effects. It has also been suggested that such frequencies may cause structural
damage to buildings. Scientific publications on these devices are not available,
leaving no hard evidence for the effects claimed.
Possible dangers posed to the operators of such devices (and their colleagues) must be
taken into consideration. Leakage, reflections from buildings and the natural spread of
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49
the sound waves will potentially have equal effects on targets, enforcement personnel
and bystanders.
It is reported that, even at low amplitudes, some frequencies (3-7Hz) can kill. At other
frequencies (7-20Hz) side-effects (to eyes and internal organs) are reported to last
several days. However, medical confirmation of the reported effects of infrasound has
not been found.
9.3.2
Acoustic shock wave devices
Combustion powered high pressure acoustic shock waves are reported to be more
directional than the loudspeaker systems described above. It is claimed that some of
these devices are capable of producing Mach disks (pulses or packets of sound
energy) of sufficient power to knock the target over. Such devices generally need to
be vehicle mounted. At least one smaller, lower-powered, device has been developed
(360 degree output, designed primarily for pest control/area exclusion with sound
levels in excess of 125dB).
This is not yet a mature technology and there is a lack of scientific evidence on the
effectiveness and risks of infrasound and acoustic shock wave devices.
9.4
Electromagnetic Waves
The US Air Force Research Laboratory has developed a device that creates a heating
effect in the skin using a beam of high frequency (95GHz), near microwave
electromagnetic radiation. The device is intended for use as an area denial or crowd
control system. A fixed installation is being tested in the US and a vehicle-mounted
version is to be developed.
The radiation generates a burning sensation in the target (reported to be like touching
a hot lightbulb) such that the target is motivated to move out of the beam. The
radiation penetrates clothing but does not enter more than one sixty-fourth of an inch
(0.4mm) into the skin. The device is intended for use in 2-second bursts and has a
reported range of 700yds (640m). It is possible that wet, heavy clothes or aluminium
shielding may be sufficient countermeasures.
Initial tests in the US on volunteers show no ill effects beyond some skin tenderness
after repeated exposure. Testing is continuing in the US throughout 2001. The
exposure time for permanent injury and results of studies of long-term effects have
not been released. It has not been reported how exposure at different distances from
the source affects the target. No studies have been carried out in damp, rainy weather
conditions. The radiation does not interfere with electrical devices (such as
pacemakers or computers).
9.5
Nets and Wire Entanglement Systems
Nets and bolas systems are designed to disable a target through entanglement. In the
case of nets the whole body may become entangled, bolas devices are designed to
affect the legs of the target. A number of devices are available commercially.
Some of the nets are supplied as 37mm cartridges to be fired from a standard weapon
or a one-shot launcher, while others rely on a specialised reusable launcher device.
50
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The bolas devices are generally fired from standard firearms such as a 12-gauge
shotgun, or even a 9mm handgun using a blank cartridge to launch the projectile.
A number of variations on the standard net are available. These include a sticky net
coated with glue to further impede motion, an irritant net where the net fibres are
coated with an irritant chemical such as OC, and an electrical net where a high voltage
electrical discharge (60kV) is passed through the net.
The claimed operational ranges for the nets vary between 2m and 9m. The nets
themselves also vary in size, with one model having a 3m diameter, while another
uses a 5m x 5m square net. Both nets employ a series of weights attached to the
outside edge for stability during flight and expand the net to the correct shape. One
model uses fifteen 25mm long flat lead weights, the other uses eight lead ball weights
enclosed in a tube of foam padding.
One available bolas device can be used in one of two ways, either as a kinetic energy
round at ranges between 2 and 15m or as an entangling device at distances between 3
and 11m. The round contains 1.7m of thin nylon rope. Other bolas systems consist of
three rubber balls connected by a few metres of thin rope. The claimed effective range
of these devices is 18-36m.
Previous small-scale testing on earlier versions of nets showed that they were
ineffective and that the target was able to tear through the net, although it is believed
that higher strength nets have been produced since then.
9.6
Glue, Foam and Grease
9.6.1
Anti-Personnel
Sticky foams (also referred to as “Stick'ems”) were investigated by Sandia National
Laboratories, USA (SNL). The foam is held under pressure until it is dispensed, when
it will expand up to 30 times its original volume on exposure to atmospheric pressure.
The foam then sets to form a rigid solid. Various compositions have been developed;
common ingredients include rubbers, resins, oils, fire retardants and stabilising
chemicals.
Trials were carried out by SNL on the use of sticky foam in prison and law
enforcement situations. A shoulder slung dispenser was developed and tested. SNL
have discontinued research on sticky foams for prison/law enforcement purposes due
to problems with decontamination and clean up, as well as fears of suffocation.
One commercial product consists of a glue contained in an aerosol can. The quoted
range for the glue spray is 7-8m with a spray time of 6-7 seconds. The glue is
intended for use in marking suspects for later identification as well as slowing the
target and inhibiting motion. The spray was developed in association with the
Japanese police authorities.
9.6.2
Area Denial
The US Army Edgewood Research and Development Engineering Centre (ERDEC)
researched aqueous foams, similar to soap suds, for area denial purposes. The foam
can be used as a visual obscurant, fire suppressant, explosive blast suppressant or
irritant carrier. Aqueous foam applications were developed by SNL for use in the
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51
nuclear industry and later, for use in prison scenarios. The foam itself is not intended
to provide an impenetrable barrier and can be easily crossed. The foam could be used
to carry an irritant chemical, as part of its chemical make-up, or to hide a more
physical barrier.
Southwest Research Institute, USA, investigated the use of rigid foams for area denial
(e.g. sealing entrances to buildings). Some commercial rigid foam systems were
developed, mainly used in high security vehicles.
Anti-traction materials (“slick'ums”) have been developed by US military researchers.
The intention is to deny access to an area by creating a slippery area of ground, which
cannot be crossed on foot or, in some cases, in vehicles. Various chemicals have been
investigated for this purpose including dry polymer powders activated by addition of
water, hydrocarbon based lubricants and Teflon or polyethylene confetti.
US Army investigations into anti-traction systems have focussed primarily on water
activated polymers as these have been shown to present few environmental or health
hazards and are easily cleared by use of high-pressure water jets. The water/polymer
mixture was found to provide satisfactory results on smooth non-porous surfaces such
as pavements, runways and well-compacted soils. Heavy rain, high temperatures and
high humidity were found to reduce effectiveness. While these materials will
effectively immobilise personnel and vehicles they will also adversely affect
emergency services until a clean-up operation is carried out.
10
CONCLUSIONS
A large amount of information has been gathered about a wide range of less lethal
options. Five main areas have been agreed as meriting immediate further research;
these are summarised as:
•
•
•
•
•
Impact Devices or Kinetic Energy Rounds
Long Range Chemical Delivery Devices
Water Cannon, both vehicle mounted and portable
Electrical Devices, particularly the taser
Distraction/Disorientation Devices, particularly laser/light devices and noise
generating devices
Evaluation of each of these areas is at an advanced stage and operational and technical
information gathered from various sources has been validated and expanded by an
intensive testing programme within PSDB. The initial phase of testing is almost
complete for most of these technologies and a number of devices have been identified
as meeting the basic criteria for further evaluation. Further testing of these devices
will continue to assess their performance against other aspects of the operational
requirement.
Those devices that meet all of the scientific and technical evaluation criteria will then
be assessed by a medical committee who will comment on their effects on the human
body. This committee will consist of a number of independent medical professionals
who have expertise in the technology or effects being considered.
52
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11
ACKNOWLEDGEMENTS
A number of PSDB staff have provided invaluable assistance in the writing,
preparation and collation of the information contained within this report. They have
carried out work on various projects within the less lethal programme, without which
this report could not have been written. They have helped research the available
technologies, gather information from manufacturers and international contacts, carry
out testing of the various devices and liase with the customers.
The following people deserve particular thanks: Dr. Karen Douse, Dr. Michelle
Gardner, Graham Smith, Graham Parker, Dr. Tracy Hart, Daniel Longhurst, Dave
Wilkinson, Matthew Symmons and Chief Inspector Neil Haynes. Additional thanks
also go to Christopher Selway and Eric Brown for their assistance.
PSDB has also drawn heavily on its overseas contacts, including organisations in the
United States, Canada and Europe. The particular organisations that have provided
assistance are detailed below.
Organisation
Amt fur Wehrtechnik
Belgian Gendarmerie
Canadian Police Research Centre
Royal Canadian Mounted Police
Victoria Police Department
Drug Law Enforcement Unit
National Commissioner of the Danish Police
Ministry of the Interior – Police Department
Police Technical Centre
Ministry of Interior
Bundeskriminalamt (BKA)
Polizei-Fuhrungsakademie (PFA)
Garda Siochana
Police Operations and Training Dept.
Politie (Police Institute for Public Order)
Rikspolisstyrelsen (Swedish National Police
Board)
Kantonpolizei Bern
Association of Chief Police Officers and many
individual police forces
Defence Science and Technology Laboratories
(dstl)
Department of Health (DoH)
Ministry of Defence
NCIS Liaison Officers
Prison Service
Qinetiq
Royal Ulster Constabulary
Air Force Research Laboratory
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Country
Austria
Belgium
Canada
Canada
Canada
Cyprus
Denmark
Finland
Finland
France
Germany
Germany
Ireland
Luxembourg
Netherlands
Sweden
Switzerland
UK
UK
UK
UK
UK
UK
UK
UK
US
53
Organisation
Joint Non Lethal Weapons Directorate
Los Angeles Sheriffs Department
National Institute of Justice
National Institute of Standards and Technology
Pennsylvania State University
United States Marine Corps at Quantico
Wayne State University
Country
US
US
US
US
US
US
US
The assistance of manufacturers and suppliers has also been invaluable, but for
commercial confidentiality reasons, a list cannot be included.
54
PSDB 12/01
12
REFERENCES
1.
‘Report of the Independent Commission on Policing for Northern Ireland’ (the
Patten Report), published September 1999.
2.
‘Patten Report Recommendations 69 and 70 Relating to Public Order
Equipment’, April 2001.
3.
J. Kenny, S. Heal and M. Grossman, ‘The Attribute Based Evaluation (ABE)
of Less-Than-Lethal, Extended-Range, Impact Munitions’, February 2001.
4.
‘Statement on the comparative injury potential of L5A7 baton round fired
from the L104 Anti-riot gun using the battle-sights, and the L21A1 baton
round fired using the XL18E3 optical sight’, Defence Scientific Advisory
Council, 21 August 2000.
5.
T.G. Sheldon and J. Tan, ‘Specification for CS Sprays for Operational Police
Use’, PSDB Publication No 2/97, 1997.
6.
E.C. Brown, ‘CS Devices for Police Use’, SRDB Publication No 33/84, 1984.
RESTRICTED
7.
J. F. Acheson, A. H. Chignell and D. Wong, ‘Eye injuries caused by directed
jets of water from a fire hose’, British Medical Journal, Volume 294, 21
February 1987.
8.
D. Berson and D. Landau, ‘Orbital Laceration caused by a blast of water:
report of two cases’, British Journal of Opthalmology, Volume 67, pages 840841.
9.
D Laur, ‘Independent Evaluation Report of Taser and Air Taser Conducted
Energy Weapons’, 10 September 1999.
10.
M.N. Robinson, C.G. Brooks and G.D. Renshaw, ‘Electric Shock Devices and
their Effects on the Human Body’, Med. Sci. Law (1990), Vol. 30, No. 4,
pages 285-300.
11.
J. Altmann, ‘Acoustic Weapons – Myths and Reality’, Jane’s Non-Lethal
Weapons Conference, November 1999.
12.
H. Sze, ‘An Acoustic Blaster Demonstration Program’, NDIA Non-Lethal
Defense III.
13.
L. Bickford, D. Bowie, K. Collins and H. Salem, ‘Odorous Substances for
Non-Lethal Applications’, NDIA Non-Lethal Weapons IV.
14.
J. Altmann. ‘Acoustic Weapons? Sources, Propagation and Effects of Strong
Sound’, Acoustical Society of America ASA/EAA/DAGA ’99 Meeting Lay
Language Papers.
15.
G. Vassilatos, ‘The sonic weapon of Vladimir Gavreau’, Borderland Sciences
Research Foundation, 1997.
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55
APPENDIX A
SUGGESTED
RESEARCH
PRIORITIES
FOR
FURTHER
This list provides a summary of the prioritisation of less lethal technologies agreed by
ACPO and the NIO in July. This list has formed the framework for the testing
programme reported in this document.
Category A
Devices which may be subject of immediate more in depth research:
1)
Medium-Range (5-20m) to Long-Range (over 20m) Devices
a)
Kinetic Energy Rounds
This generic category includes sponge grenades, bean bags, sock rounds and
single and multiple ball rounds. This category also includes the new L21A1
baton round, acknowledged as the most accurate round in its class and
currently available for use. (Note, the L21A1 has not been included in this
study as extensive testing has already been carried out for this round).
b)
Discriminating Chemical Delivery Devices/Rounds
These devices/rounds can be used to deliver a quantity of chemical irritant
(e.g. CS) to a target at an extended range, i.e. further than is possible using
conventional hand held sprays (10-14ft). These tend to combine kinetic impact
effects with chemical irritant effects to produce incapacitation of the target.
The degree of each effect varies with each system and is dependent on the
velocity, size, shape, material etc. of the round and also the quantity of irritant
contained within it.
2)
3)
Water Cannon
Conventional vehicle mounted water cannon are in use throughout Europe and
in other parts of the world. Work has been carried out by the Home Office
between 1981 and 1987 but was discontinued by the then Home Secretary. A
review of all currently available vehicle mounted and portable water cannon is
underway to identify those systems which most closely meet the operational
requirements of the UK police.
Electrical Devices (e.g. Tasers)
Electrical devices include any weapons that use the effects of electricity to
incapacitate the target. There are a variety of different devices but their
principle of operation is the same. They are battery powered and use a low
current, high voltage impulse shock for incapacitation. The electrical stimulus
delivered by the device interferes with the normal electrical signals generated
by the human nervous system. Incapacitation by electrical means appears to
offer a virtually instantaneous method of incapacitation with almost instant
recovery, although some questions remain on delivery methods and on health
effects. Priority has been given to those devices that can be used at a range, for
example the taser.
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4)
Laser/Light Devices
The effects of bright light/laser devices can range from dazzle or glare to
image formation, flashblindness and irreversible damage. Generally, these
devices do not incapacitate a person, although there may be some deterrent
effect as the target becomes aware that he/she has been picked out. A device
that dazzles at large distances may cause irreversible damage at close range.
These devices are considerably less effective in daylight or in the presence of
strong artificial light.
5)
Noise Generating Devices
The potential of loud noise to distract and disorient is well known and can be
incorporated into devices that are either hand thrown or fired from weapons.
The requirement is for a non-fragmenting and non-pyrotechnic device that will
provide a potentially less injurious alternative to the more traditional stun
grenade.
Category B
Devices warranting further research over a more extended time frame:
1)
Malodorants
Malodorants may be of assistance in dispersing crowds although they are
unlikely to prevent a determined assailant at short range. There may be issues
about decontamination following deployment, especially in residential or
heavily populated areas. The possibility of developing malodorous devices
appears not to have been fully explored and exploration of this technology will
necessarily be longer term. There may also be toxicological considerations for
these types of device.
2)
Tranquillisers
The speed of reaction to any anaesthetic or drug will be an important factor in
its use, as will the possibility that different people will react differently to it
and the dose required to incapacitate one person may prove harmful to another.
Category C
Devices which presently do not require further research:
1)
Stun Grenades
These devices could be considered to be too indiscriminate and potentially
dangerous.
2)
Smoke
These devices could be considered to be too indiscriminate and potentially
dangerous.
3)
Acoustic Devices
This is not yet a mature technology and there is a lack of scientific evidence on
the effectiveness and risks of infrasound and acoustic shock wave devices.
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4)
Electromagnetic Waves
This device is still subject to further development. It may also be potentially
easily countered by adequate protection by the subjects.
5)
Nets and Wire
Potentially injurious due to the indiscriminate nature of the necessary weights
attached to the devices.
6)
Glue, Foam and Grease
Problems would appear to exist with respect to potential suffocation of
subjects, decontamination and exclusion of emergency services as well as
disorderly/dangerous individuals.
PSDB 12/01
APPENDIX B
A
GLOSSARY OF TERMS
ACRONYMS and ABBREVIATIONS
ABE
Attribute Based Evaluation
AC
Alternating Current
ACPO
Association of Chief Police Officers
CDE
Chemical Defence Establishment
CN
Chloroacetophenone
CR
Dibenz (b.f.)-1:4-oxazepine
CS
O-Chlorobenzylidene Malononitrile
HO
Home Office
LASD
Los Angeles Sheriff’s Department
Laser
Light Amplification by the Stimulated Emission of Radiation
LED
Light Emitting Diode
MPE
Maximum Permissible Exposure
NIJ
National Institute of Justice
NIO
Northern Ireland Office
OC
Oleoresin Capsicum
PAVA
Pelargonic Acid Vanillylamide
PBR
Plastic Baton Round (now generally referred to as baton round)
PSDB
Police Scientific Development Branch
PTSD
Police Technical Services Division
rms
Root mean square
RUC
Royal Ulster Constabulary
SRDB
Scientific Research and Development Branch
Taser
Thomas A Swift’s Electrical Rifle (from the Tom Swift fantasy stories)
B
TECHNICAL TERMS
Ampere (A)
The basic SI unit of electric current.
Bar
Unit of pressure in the C.G.S. system. 1 bar = 1x105 newtons per
square metre.
C.G.S. system
Centimetre-gram-second system. A system of physical units derived
from the centimetre, gram mass and the second.
Candela
The SI unit of luminous intensity (the amount of light emitted per
second in unit solid angle by a point source, in a given direction).
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dB
Decibel, a measure of sound intensity. One decibel = one tenth of a
bel.
Electric
Current
An electric current is said to flow through a conductor when there is
an overall movement of electrons through it. The SI unit of current is
the ampere.
Energy
The capacity for doing work. The various forms of energy,
interconvertible by suitable means, include potential, kinetic,
electrical, heat, chemical, nuclear and radiant energy.
Interconversion between these forms of energy can only occur in the
presence of matter. Energy can only exist in the absence of matter in
the form of radiant energy. The derived SI unit of energy is the
joule.
Erythema
A general term signifying several conditions in which areas of the
skin become congested with blood, and consequently a red eruption
appears. The eruption is accompanied by tingling, and often by
itching and pain.
Hertz (Hz)
The derived SI unit of frequency. Defined as the frequency of a
periodic phenomenon of which the periodic time is one second;
equal to 1 cycle per second.
Joule (J)
The derived SI unit of work or energy. The work done when the
point of application of a force of 1 newton is displaced through a
distance of 1 metre in the direction of the force. The joule is also the
work done per second by a current of 1 ampere flowing through a
resistance of 1 ohm.
Kinetic
Energy (KE)
The energy which a body possesses by virtue of its motion. The
kinetic energy of a mass m, moving with velocity v, is ½mv2.
Metre (m)
The SI unit of length.
Ohm
The derived SI unit of resistance defined as the resistance between
two points of a conductor when a constant difference of potential of
1 volt, applied between these two points, produces in the conductor a
current of 1 ampere.
Pascal (Pa)
The derived SI unit of pressure, equal to 1 newton per square metre.
Photokeratitis
Inflammation of the cornea in front of the eye due to light.
Power
The rate of doing work, measured in units of work per unit time. The
derived SI unit of power is the watt.
Rt
Total resistance.
Second (s)
The SI unit of time.
SI units
An internationally agreed coherent system of units now in use for all
scientific purposes.
Volt (V)
The derived SI unit of electric potential. Defined as the difference of
potential between two points on a conducting wire carrying a
constant current of one ampere when the power dissipated between
these points is one watt. Also the unit of potential difference and
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electromotive force.
Voltage
The potential, potential difference or electromotive force of a supply
of electricity, measured in volts.
Watt (W)
The derived SI unit of power, equal to one joule per second.
Waveform
The shape of a wave, illustrated graphically by plotting the values of
the periodic quantity against time.
C
METRIC (SI) MULTIPLIERS
Giga (G)
109
Mega (M)
106
Kilo (k)
103
Deci (d)
10-1
Centi (c)
10-2
Milli (m)
10-3
Micro (µ)
10-6
Nano (n)
10-9
Pico (p)
10-12
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POLICE SCIENTIFIC DEVELOPMENT BRANCH
Sandridge, St. Albans, Hertfordshire AL4 9HQ, UK
Telephone: +44 (0)1727 865051 Fax: +44 (0)1727 816233
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