MAY 2011

U.S. Department of Justice
Office of Justice Programs
National Institute of Justice

Research in B r i e f

Police Use of Force, Tasers and Other Less-Lethal Weapons
www.nij.gov

U.S. Department of Justice
Office of Justice Programs
810 Seventh Street N.W.
Washington, DC 20531

Eric H. Holder, Jr.
Attorney General
Laurie O. Robinson
Assistant Attorney General
John H. Laub
Director, National Institute of Justice

This and other publications and products of the
National Institute of Justice can be found at:
National Institute of Justice
www.nij.gov

Office of Justice Programs
Innovation • Partnerships • Safer Neighborhoods
www.ojp.usdoj.gov

NIJ

May 2011

Police Use of Force, Tasers and Other
Less-Lethal Weapons

Findings and conclusions of the research reported here are those of the
authors and do not necessarily reflect the official positions or policies of the
U.S. Department of Justice.
This Research in Brief is based primarily on “A Multi-Method Evaluation
of Police Use of Force Outcomes,” final report to the National Institute of
Justice, July 2010, NCJ 231176, available online at http://www.ncjrs.gov/
pdffiles1/nij/grants/231176.pdf.
This research was supported by grant number 2005–IJ–CX–0056 from the
National Institute of Justice.

NCJ 232215

RESEARCH IN BRIEF / MAy 2011

About this report
This study looked at injuries
that occur to law enforce­
ment officers and citizens
during use-of-force events.
Most applications of force
are minimal, with officers
using their hands, arms or
bodies to push or pull against
a suspect to gain control.
Officers are also trained
to use various other force
techniques and weapons to
overcome resistance. These
include less-lethal weapons
such as pepper spray, batons
or conducted energy devices
(CEDs) such as Tasers. They
can also use firearms to
defend themselves or others
against threats of death or
serious bodily injuries.

What did the
researchers find?
This study found that when
officers used force, injury
rates to citizens ranged from
17 to 64 percent, depending
on the agency, while officer
injury rates ranged from 10
to 20 percent. Most injuries
involve minor bruises, strains
and abrasions.

ii

The study’s most significant
finding is that, while results
were not uniform across all
agencies, the use of pep­
per spray and CEDs can
significantly reduce injuries
to suspects and the use of
CEDs can decrease injuries
to officers.
The researchers assert that
all injuries must be taken se­
riously. When police in a de­
mocracy use force and injury
results, concern about police
abuse arises, lawsuits often
follow and the reputation
of the police is threatened.
Injuries also cost money in
medical bills for indigent sus­
pects, workers’ compensa­
tion claims for injured officers
or damages paid out in legal
settlements or judgments.

What were the study’s
limitations?
In many cases, agencysupplied injury data did not
allow for a detailed analysis
of the nature or seriousness
of the injuries reported.

PolICE USE oF FoRCE

Geoffrey P. Alpert, Michael R. Smith, Robert J. Kaminski,
Lorie A. Fridell, John MacDonald, and Bruce Kubu

police use of Force, tasers and
other Less-Lethal Weapons
introduction
Police weaponry has come
full circle.

About the Authors
Geoffrey P. Alpert,
Ph.D., is professor of
criminology and criminal
justice at the University
of South Carolina.
Michael R. Smith, J.D.,
Ph.D., is professor of
political science and
dean of the College of
Liberal Arts and Social
Sciences at Georgia
Southern University.
Robert J. Kaminski, Ph.D.,
is associate professor of
criminology and criminal
justice at the University of
South Carolina. Lorie A.
Fridell, Ph.D., is associate
professor of criminology
at the University of
South Florida. John
MacDonald is associate
professor of criminology
at the University of
Pennsylvania. Bruce
Kubu is senior research
associate at the Police
Executive Research
Forum.

During the middle of the
19th century, police officers
in New York and Boston
relied on less-lethal weapons,
mostly wooden clubs. By late
in the century, police depart­
ments began issuing firearms
to officers in response to bet­
ter armed criminals. Although
firearms are still standard
issue, law enforcement agen­
cies are again stressing the
use of less-lethal weapons
rather than firearms.1
The Fourth Amendment for­
bids unreasonable searches
and seizures, and various
other legal and policy con­
trols govern how and when
officers can use force. Most
agencies tightly control the
use of force and supervi­
sors or internal affairs units
routinely review serious
incidents. New technologies
have added to the concerns
about the use of force by law
enforcement.

New technologies
raise questions
During the past 20 years,
new technologies have
emerged that offer the
promise of more effective
control over resistive sus­
pects with fewer or less
serious injuries. Pepper spray
was among the first of these
newer less-lethal weapons to
achieve widespread adoption
by police forces, and more
recently, conducted energy
devices (CEDs) such as the
Taser have become popular.
Taser use has increased
in recent years. More than
15,000 law enforcement and
military agencies use them.
Tasers have caused contro­
versy (as did pepper spray)
and have been associated
with in-custody deaths and
allegations of overuse and
intentional abuse. Organi­
zations such as Amnesty
International and the Ameri­
can Civil Liberties Union have
questioned whether Tasers
can be used safely, and what
role their use plays in injuries
and in-custody deaths.

1

RESEARCH IN BRIEF / MAy 2011

Several studies
found that
when agencies
adopted the
use of pepper
spray, they
subsequently
had large
declines in
assaults on
officers and
declines in
officer and
suspect injury
rates, and
associated
injuries were
usually minor.
Pepper spray
provides a
way to reduce
injuries.

2

CEDs such as Tasers pro­
duce 50,000 volts of electric­
ity. The electricity stuns and
temporarily disables people
by causing involuntary mus­
cle contractions. This makes
people easier to arrest or
subdue. When CEDs cause
involuntary muscle contrac­
tions, the contractions cause
people to fall. Some people
have experienced serious
head injuries or bone breaks
from the falls, and at least
six deaths have occurred
because of head injuries suf­
fered during falls following
CED exposure. More than
200 Americans have died af­
ter being shocked by Tasers.
Some were normal, healthy
adults; others were chemi­
cally dependent or had heart
disease or mental illness.2
Tasers use compressed nitro­
gen to fire two barbed probes
(which are sometimes called
darts) at suspects. Electric­
ity travels along thin wires
attached to the probes. (A
new wireless Taser is also on
the market.) Darts may cause
puncture wounds or burns. A
puncture wound to the eye
could cause blindness.3
Despite the dangers, most
CED shocks produce no seri­
ous injuries. A study by Wake
Forest University researchers
found that 99.7 percent of
people who were shocked by

CEDs suffered no injuries or
minor injuries only. A small
number suffered significant
and potentially lethal injuries.
This NIJ-sponsored study
included six police depart­
ments and evaluated the
results of 962 “real world”
CED uses. Skin punctures
from CED probes were
common, accounting for 83
percent of mild injuries.4
Policymakers and law en­
forcement officials want to
know whether Tasers are
safe and effective, and how
(if at all) they should be used
to match police use-of-force
choices with levels of sus­
pect resistance. This study
indicates that CED use actu­
ally decreases the likelihood
of suspect injury.

previous research
on use of force and
injuries
The controversy around
Taser use is not unique. Law
enforcement agencies found
themselves in similar circum­
stances with pepper spray
in the 1990s. Human rights
groups such as Amnesty
International questioned the
safety and misuse of pepper
spray as its use spread
rapidly in American law
enforcement agencies. NIJ

PolICE USE oF FoRCE

funded various studies on the
safety and effectiveness of
pepper spray.5
Some studies have focused
on officer injury. Several
found that about 10 percent
of officers were injured when
force was used.6 However,
two studies of major police
departments found officer
injury rates of 38 and 25
percent.7 The agencies with
lower rates allowed officers
to use pepper spray, while
the two with higher rates
did not.
A few researchers have
looked at how various ap­
proaches to force affect of­
ficer injury rates.8 Overall, the
empirical evidence shows
that getting close to sus­
pects to use hands-on tactics
increases the likelihood of
officer injuries. Research also
shows that suspects have
a higher likelihood of injury
when officers use canines,
bodily force or impact weap­
ons such as batons. Alter­
natives to bodily force and
impact weapons are found
in other less-lethal weapons
such as pepper spray and
CEDs.

Previous studies on
pepper spray and CEDs
Pepper spray. Law en­
forcement agencies rapidly

I

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adopted pepper spray in the
late 1980s and early 1990s
as an alternative to traditional
chemical agents such as tear
gas, but its use sparked con­
troversy. Notably, the Ameri­
can Civil Liberties Union of
Southern California asserted
that pepper spray was caus­
ing in-custody deaths. NIJ
studies on the link between
pepper spray and in-custody
deaths found that the deaths
were largely a result of posi­
tional asphyxia, pre-existing
health conditions or were
drug related.9
Several studies found that
when agencies adopted the
use of pepper spray, they
subsequently had large
declines in assaults on of­
ficers and declines in officer
and suspect injury rates,
and associated injuries were
usually minor.10 Pepper spray
provides a way to reduce
injuries.
CEDs. Many law enforce­
ment agencies noted that
injury rates for officers and
suspects declined after they
introduced CEDs.11
Medical research, including
controlled animal trials and
controlled human trials, has
produced various insights.
Some animal studies were
conducted to learn if CED
3

RESEARCH IN BRIEF / MAy 2011

use could result in ventricular
fibrillation. Several studies
showed that standard shocks
that lasted five to 15 seconds
did not induce ventricular fi­
brillation of the heart. Higher
discharges, 15 to 20 times
the standard, or those of
longer duration — two 40second exposures — induced
fibrillation or increased heart
rhythm in some pigs. In addi­
tion, longer exposures led to
ventricular fibrillation-induced
death in three pigs.12
Controlled studies involv­
ing healthy human subjects
(often law enforcement
trainees) found that sub­
jects experienced significant
increases in heart rates fol­
lowing exposure, but none
experienced ventricular
fibrillation.13

NiJ study and
recommendations
NIJ gathered an expert panel
of medical professionals
to study in-custody deaths
related to CEDs. In its report,
the panel said that while CED
use is not risk free, there is
no clear medical evidence
that shows a high risk of
serious injury or death from
the direct effects of CEDs.
Field experience with CED
use shows that exposure
is usually safe. Therefore,
4

law enforcement agencies
need not avoid using CEDs
provided they are used in
line with accepted national
guidelines.14
A preliminary review of
deaths following CED expo­
sure found that many are as­
sociated with continuous or
repeated shocks. There may
be circumstances in which
repeated or continuous
exposure is required, but law
enforcement officers should
be aware that the associated
risks are unknown. There­
fore, caution is urged in using
multiple activations.15
The seeming safety mar­
gins of CED use on normal
healthy adults may not be
applicable to small children,
those with diseased hearts,
the elderly, those who are
pregnant and other at-risk
people. The use of CEDs
against these populations
(when recognized) should be
avoided, but may be neces­
sary if conditions exclude
other reasonable choices.16
A suspect’s underlying
medical conditions may be
responsible for behavior that
leads law enforcement of­
ficers to subdue him or her.
Sometimes this includes CED
use. Abnormal mental status
in a combative or resistive
subject, sometimes called

PolICE USE oF FoRCE

“excited delirium,” may be as­
sociated with a risk for sudden
death. This should be treated
as a medical emergency.17

the national survey
The Police Executive Re­
search Forum conducted a
survey of state, county and
municipal law enforcement
agencies to learn more about
less-lethal technologies and
related policies and train­
ing. More than 500 agencies
participated.
Most agencies have a “use­
of-force continuum” that is
covered in training, where
officers learn to use suitable
force levels depending on
circumstances. For example,
an officer might start by us­
ing verbal commands when
dealing with a suspect. Then
an officer might move to soft
empty-hand tactics (such as
pushing) when faced with
lack of cooperation or mild
resistance. The continuum
covers various circumstances
up to the use of firearms.
The survey included vari­
ous levels of resistance and
asked agencies to describe
what force they allow in
each. Most agencies allow
only soft tactics against a
subject who refuses, without
physical force, to comply

with commands. Just under
half allow officers to use
chemical weapons at that
point. However, if the subject
tensed and pulled when an
officer tried to handcuff him
or her, most agencies would
allow chemical agents and
hard empty-hand tactics,
such as punching. Many also
allow for CED use at this
point but about 40 percent
do not. Almost three-fourths
allow CED use if the suspect
flees, and almost all allow it
when the subject assumes a
boxer’s stance. Most agen­
cies do not allow baton use
until the subject threatens
the officer by assuming the
boxer’s stance.
Three-fourths of the sur­
veyed agencies that use
CEDs issued them between
2004 and 2006. Most are
using Tasers. In most agen­
cies, officers receive four or
six hours of training, and 63.7
percent of agencies require
that officers experience
activation (i.e., get shocked)
during training.
Most agencies do not allow
CED use against a subject
who nonviolently refuses
to comply with commands.
However, six in 10 allow for
CED use against a subject
who tenses and pulls when
the officer tries to handcuff
him or her. Agencies usually

I

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The seeming
safety margins
of CED use on
normal healthy
adults may not
be applicable to
small children,
those with
diseased hearts,
the elderly,
those who are
pregnant and
other at-risk
people. The
use of CEDs
against these
populations
(when
recognized)
should be
avoided but may
be necessary
if conditions
exclude other
reasonable
choices.

5

RESEARCH IN BRIEF / MAy 2011

place the CED with chemical
agents in their force contin­
uum, meaning that their use
is typically approved in the
same circumstances in which
pepper spray use is allowed.
CEDs are usually lower on
the continuum than impact
weapons.
One facet of the contro­
versy surrounding CED use
concerns vulnerable popula­
tions and circumstances that
pose potentially heightened
risk to the subject. For only
one circumstance — when
a subject is near flammable
substances — do most agen­
cies (69.6 percent) ban CED
use.
Some 31 percent forbid CED
use against clearly pregnant
women, 25.9 percent against
drivers of moving vehicles,
23.3 percent against hand­
cuffed suspects, 23.2 percent
against people in elevated
areas and 10 percent against
the elderly. However, many
agencies, while not forbid­
ding use in these circum­
stances, do restrict CED use
except in necessary, special
circumstances.

6

Analysis of information
from specific law
enforcement agencies
Looking at the experiences
of specific agencies can yield
important information that
might otherwise be lost in
larger analyses. The research­
ers used various statistical
techniques to identify factors
that increase or decrease the
odds of injury to officers and
suspects alike.
Richland County Sheriff’s
Department. The Richland
County Sheriff’s Department
(RCSD) includes about 475
sworn officers who serve the
unincorporated portions of
Richland County, S.C. Depu­
ties carry Glock .40 caliber
pistols, collapsible metal
batons and pepper spray.
Increasingly, they also carry
the model X-26 Taser. The
agency started phasing in
Taser use in late 2004. Dur­
ing data collection, about 60
percent of deputies carried
Tasers.
Researchers coded 467 use­
of-force reports covering the
period from January 2005 to
July 2006. Of the 49 separate
injuries recorded for officers
(three officers had more
than one injury), 46 involved
bruises, abrasions or cuts.
The department recorded 92

PolICE USE oF FoRCE

suspect injuries; 69 of those
were bruises, abrasions or
cuts. Most of the remaining
suspect injuries were dog
bites, but three involved
broken bones or internal
injuries.
Further analysis of the data
included identifying how
various factors increased or
decreased the risk of injury
to officers or suspects. The
use of soft empty-hand
techniques by an officer, ac­
tive aggression by a suspect
and suspect use of deadly
force all increased the risk for
deputies.
Soft empty-hand control was
the most frequent force level
used by deputies, occurring
in 59 percent of all use-of­
force incidents. These tech­
niques increased the odds of
officer injury by 160 percent.
Thus, deputies were at great­
est risk for injury when using
the least force possible.
Two variables significantly
decreased the risk for
suspects. Pepper spray
use decreased the odds of
suspect injury by almost 70
percent, and a deputy aiming
a gun at a suspect reduced
injury odds by more than 80
percent (because the act of
pointing a gun alone often
effectively ends the sus­
pect’s resistance).

I

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However, the use of a canine
posed, by far, the great­
est injury risk to suspects,
increasing injury odds by al­
most 40 fold. Suspects who
displayed active aggression
toward deputies were also
more likely to suffer injuries.
CED use had no effect on
the likelihood of injury; this is
inconsistent with the experi­
ences of other agencies,
suggesting that not every
agency’s experience with the
Taser will be the same.
Miami-Dade Police
Department. The depart­
ment has about 3,000
officers, is the largest law
enforcement agency in the
Southeast and is one of the
largest departments that has
never issued pepper spray to
its officers.18
The researchers examined
762 use-of-force incidents
involving a lone officer and a
lone suspect that occurred
between January 2002 and
May 2006. About 70 percent
of the officers carried Tasers
by May 2006. Officers were
substantially less likely to be
injured than suspects, with
16.6 percent (124) of officers
injured and 56.3 percent
(414) of suspects injured.
Most injuries were minor, but
73 suspects (17 percent)

7

RESEARCH IN BRIEF / MAy 2011

suffered serious injuries. Mi­
nor injuries included bruises,
sprains and lacerations.
Major injuries included bites,
punctures, broken bones,
internal injuries and gunshot
wounds.
The department does not
issue pepper spray to its
line officers, and there were
few incidents involving guns
or batons. Analysis of the
incidents found that the use
of both soft-hand tactics and
hard-hand tactics by officers
more than doubled the odds
of officer injury. Conversely,
CED use was associated with
a 68-percent reduction in the
odds of officer injury.
As for suspects, hands-on
tactics increased the odds
of injury, the use of canines
greatly increased the odds
and CED use substantially
decreased the odds.
Seattle Police Department.
The Seattle Police Depart­
ment has about 1,200 sworn
officers. The agency started
using Tasers in December
2000. Other less-lethal
weapons include pepper
spray, batons and shotgun
beanbag rounds. The depart­
ment recorded 676 use-of­
force incidents between
Dec. 1, 2005, and Oct. 7,
2006. Suspects suffered
injuries in 64 percent of the
8

incidents, while officers suf­
fered injuries in 20 percent
of the incidents. Officers
used hands-on tactics in 76
percent of the incidents. The
next most frequent type of
force officers used was the
Taser (36 percent), followed
by pepper spray (8 percent).
Suspects were impaired
by alcohol, drugs or mental
illness in 76 percent of the
incidents. Just over half (52
percent) of the suspects
were nonwhite, and 95 per­
cent were male. Analysis of
the data revealed that Taser
use was associated with a
48-percent decrease in the
odds of suspect injury but did
not affect officer injury.
The use of unarmed tactics
by officers increased the
odds of officer injury 258
percent. The odds of officer
injury increased significantly
when suspects resisted us­
ing physical force or the use
or threat of use of a weapon.
Although results were not
uniform across the agen­
cies, the analysis shows that
the use of pepper spray and
CEDs can have a significant
and positive injury-reduction
effect.
Interestingly, nonwhite sus­
pects were less likely to be
injured than whites in both

PolICE USE oF FoRCE

agencies (Miami and Seattle)
where suspects’ race was
available as a variable for
analysis. Another important
finding concerns the use of
canines. While canines were
used rarely, their use sub­
stantially increased the risk of
injury to suspects in two of
the agencies.

Combined agency analysis
and its limitations
The researchers also con­
ducted a combined analysis
of use-of-force data from 12
large local law enforcement
agencies.19 The full report
gives a detailed description
of the information available
and the limits of the data.
Most agencies, for example,
had details about demograph­
ic characteristics of suspects,
but only four had officer
demographic information.
Moreover, the Miami-Dade
Police Department did not
use pepper spray while San
Antonio did not use CEDs.
Despite the limitations, the
study’s use of a large sam­
ple, representing more than
25,000 use-of-force incidents,
allowed the researchers to
use statistical techniques
in an effort to learn which
variables are likely to affect
injury rates to officers and
suspects. The use of physi­
cal force (hands, feet, fists)

I

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by officers increased the
odds of injury to officers and
suspects alike. However,
pepper spray and CED use
decreased the likelihood of
suspect injury by 65 and 70
percent respectively. Officer
injuries were unaffected by
CED use, while the odds of
officer injury increased about
21 percent with pepper spray
use.
The researchers noted the
12-agency analysis yielded
puzzling results about the
relationship between pep­
per spray use and officer
injury rates. Those results
are inconsistent with the
single agency analysis. More
research may explain the
differences.

Longitudinal analysis
The researchers reviewed
use-of-force information from
police departments in Austin,
Texas, and Orlando, Fla., to
learn how introducing CEDs
affected injury rates. This
quasi-experimental approach
tracked injuries before and
after CED introduction.
The Orlando data include
4,222 incidents covering
1998 to 2006. CED use
began in February 2003. The
Austin data includes 6,596
incidents from 2002 to 2006.
However, CED use was
9

RESEARCH IN BRIEF / MAy 2011

phased in beginning in 2003
and was not completed until
June 2004. A large drop in
injury rates for suspects and
officers alike occurred in
both cities following CED
introduction.
In both cities, Taser adop­
tion was associated with a
statistically significant drop
in average monthly injuries
to suspects. In Orlando, the
suspect injury rate dropped
by more than 50 percent
compared to the pre-Taser
injury rate. In Austin, suspect
injury rates were 30 percent
lower after full-scale Taser
deployment.
In Orlando, the decline in
officer injury rates were even
greater than for suspects;
the average monthly rate
dropped by 60 percent after
Taser adoption. In Austin,
officer injuries dropped by
25 percent.

Interviews with officers
and suspects
Researchers conducted inter­
views with 219 officers from
South Carolina’s Richland
County Sheriff’s Department,
35 from the Columbia Police
Department (CPD), and 35
suspects involved in use-of­
force situations to supple­
ment and add a qualitative
context to their quantitative
10

analyses. Generally, they
tried to contact officers and
suspects within 48 hours
of receiving a use-of-force
report. Interviews were
voluntary, and some officers
and suspects declined to
participate.
In nine out of 105 use-of­
force incidents, Richland
County Sheriff’s Department
officers reported that a Taser
did not work properly or did
not have the desired effect.
In addition, researchers
received reports of multiple
Taser hits on a suspect and
multiple uses of the Taser
in “drive stun” mode (when
the Taser is pressed against
a suspect rather than firing
darts) to control suspects
(or, based on the suspects’
reports, as punishment).
These reports indicate that
some officers are using Tas­
ers multiple times during an
encounter.
Nine percent of the officers
reported injuries, almost all of
which were scrapes, cuts or
bruises suffered while strug­
gling with resistant suspects.
Officers also reported that 26
suspects (12 percent) were
injured. Most suspect injuries
were cuts or abrasions, but
there were also two dog
bites, and one suspect was
shot in the arm after firing at
officers.

PolICE USE oF FoRCE

In 22 cases, researchers
interviewed both the officers
and suspects involved in an
incident. Most suspects said
officers used excessive or
unnecessary force to sub­
due them. Some suspects
said officers used Tasers
quickly, and several said the
officers enjoyed watching
them endure the pain. Some
suspects said officers kneed
them in the back and kicked
or punched them after they
were in handcuffs. Some
also said officers used Tas­
ers on them after they were
handcuffed.
Suspects often tell a different
story than the officers who
arrest them. In almost all
cases, suspects said officers
used excessive force and
that they were not resisting
arrest. The officers, for their
part, said they used minimal
force to control suspects,
and did not mention using
force after a suspect was un­
der control. Officers reported
that the force used was
necessary and reasonable. In
a typical account, a suspect
said he was unaware there
was a warrant out for his ar­
rest, and when police con­
fronted him, he did not resist.
He said the officers “pushed
me to the ground and put the
cuffs on … they didn’t have

I

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to do that to me.” He said
that all the officers had to do
was tell him to “quit acting
up.” He complained that
officers should just have told
him to calm down instead of
pushing him to the ground.
By contrast, they said the
suspect ran away when con­
fronted, so they tackled him.
These kinds of contradictions
were common; suspects said
they did not resist, and offi­
cers provided justification for
the force levels they used.
In other cases, suspects
and officers offered radically
different versions of events.
For example, in one case, an
officer said he saw several
traffic violations and the sus­
pects sped off and stopped,
with one suspect running
away. The officers said the
driver then tried to exit the
vehicle from the passenger’s
side holding a shotgun. One
officer pointed his weapon
at the suspect, who then
dropped the shotgun. The
suspect failed to mention
the shotgun to researchers
and only complained that
officers put the handcuffs
on too tightly and slammed
him around in the back of the
transport vehicle.
Unlike the Richland County
Sheriff’s Department, the

11

RESEARCH IN BRIEF / MAy 2011

Columbia Police Depart­
ment did not use Tasers.
The officers described 35
use-of-force incidents. Three
officers reported that pepper
spray was ineffective. In all
three cases, the suspects
were either drunk or high on
drugs. One case, in particu­
lar, highlighted the potential
advantages of the Taser over
pepper spray in some circum­
stances. In that case, a 6’7”,
370-pound man wanted for
domestic violence charged
an officer with a metal object
in his hand. The officer used
pepper spray, but it had no
effect. The suspect then
retreated to the apartment
kitchen and grabbed a knife.
The officers pointed their
guns at him and ordered
him to drop the knife, but he
refused. He cut and stabbed
himself with the knife while
the officers waited for an­
other agency to arrive that
was equipped with a Taser.
The suspect cut himself
more than 100 times be­
fore the South Carolina Law
Enforcement Division arrived
and used a Taser on him. The
Taser had an instant effect,
and officers were then able
to handcuff the suspect.
Most injuries in both agen­
cies occurred when officers
and suspects struggled on

12

the ground. The differences
between the agencies were
striking. RCSD equips most
of its deputies with Tasers.
The deputies collectively
reported fewer injuries to
themselves and suspects
from ground fighting than
did CPD officers. CPD did
not issue Tasers, and 31
percent of its officers report­
ed getting cuts, scrapes and
bruises from wrestling with
suspects on the ground. The
prevalence of ground fighting
injuries among RCSD officers
(less than nine percent) was
lower, as were injuries to
suspects caused by contact
with the ground. Some of
the injuries could have been
prevented had officers used
Tasers instead of hands-on
tactics.

Implications for policy,
training and future
research
Because of the controversial
nature and widespread use
of CEDs, the researchers
explored their use in detail
and made recommenda­
tions, based on the findings,
for whether and how CEDs
should fit into the range of
less-lethal force alternatives
available to law enforcement
officers.

PolICE USE oF FoRCE

Factors affecting
injuries
Physical force
The findings clearly show
the use of physical force and
hands-on control increase the
risk of injury to officers and
suspects. In Richland County,
S.C., soft empty-hand control
significantly increased the
odds of injury to officers,
while hard empty-hand
tactics increased the risk of
injury to suspects. In MiamiDade, both types of force
increased the risk of injury to
both officers and suspects.
In Seattle, use of force in­
creased injury risk to officers
but not to suspects, while
the overall analysis (of 12
agencies) showed increased
injury risk to suspects and
especially to officers associ­
ated with physical force. This
increased risk was large.
When controlling for the use
of CEDs and pepper spray
in the overall analysis, using
force increased the injury
odds to officers by more than
300 percent and to suspects
by more than 50 percent.

Suspect resistance
Increasing levels of suspect
resistance were associated
with an increased risk of

I

/J

injury to officers and sus­
pects. The increased injury
risk was especially acute for
officers. In Richland County,
active aggression and threats
of deadly force increased
the odds of officer injury
by more than 100 percent.
The odds of suspect injury
were unchanged in Seattle
with increased resistance
levels. These findings sug­
gest that officers, rather than
suspects, face the most
increased injury risk when
suspects resist more
vigorously.

Pepper spray
The findings suggest that,
at least for suspects, pepper
spray use reduces the likeli­
hood of injury. In Richland
County, pepper spray use
reduced the odds of suspect
injury by 70 percent but did
not affect officer injuries. In
Seattle, pepper spray use
had no effect on injury rates
for officers or suspects.
However, the overall analysis
(of 12 agencies) showed that
pepper spray use reduced
the likelihood of injury to
suspects by 70 percent,
which was even more than
the decline noted with CEDs
(see below). For officers,
pepper spray use increased
the likelihood of injury by 21
to 39 percent. This finding
13

RESEARCH IN BRIEF / MAy 2011

was unexpected, and more
research may help to explain
how officers choose to use
pepper spray versus CEDs.

CEDs
Except for in Richland
County where its effects
were insignificant, CED use
substantially decreased the
likelihood of suspect injury.
In Miami-Dade, the odds of
a suspect being injured were
almost 90 percent lower
when a CED was used than
when it was not. Similarly,
the odds of suspect injury
went down by almost 50
percent when CEDs were
used in Seattle. The larger
analysis of 12 agencies and
more than 24,000 use-of­
force cases showed the odds
of suspect injury decreased
by almost 60 percent when
a CED was used. In Richland
County, Seattle, and in the
larger analysis, Taser use had
no effect on officer injuries,
while in Miami-Dade, officer
injuries were less likely when
a Taser was used. Controlling
for other types of force and
resistance, CED use signifi­
cantly reduced the likelihood
of injuries. CED adoption by
the Orlando and Austin police
departments reduced injuries
to suspects and officers over
time.

14

Demographic
characteristics
Apart from officer force and
suspect resistance, few
other factors influenced
injury outcomes. In MiamiDade, male suspects were
twice as likely to be injured
as females. The same held
true for the 12-agency analy­
sis. In that larger analysis, the
presence of a male suspect
slightly increased injury risk
to officers. In Seattle, female
officers were more than
twice as likely to be injured
as male officers.

placement of pepper
spray and CeDs on a
linear use-of-force
continuum
People rarely die after being
pepper sprayed or shocked
with a Taser. However, if
injury reduction is the primary
goal, agencies that allow use
of these less-lethal weapons
are clearly at an advantage.
Both weapons prevent or
minimize the physical strug­
gles that are likely to injure
officers and suspects alike.
Although both cause pain,
they reduce injuries, and
according to current medical
research, death or serious
harm associated with their

PolICE USE oF FoRCE

use is rare. In that sense,
both are safe and similarly
effective at reducing inju­
ries. Both should be allowed
as possible responses to
defensive or higher levels
of suspect resistance. This
recommendation is sup­
ported by the findings and
is now followed by most
agencies that responded to
the national survey.

policy and training
issues related to CeDs
CEDs were used far more
often (four to five times
more often) than pepper
spray among agencies that
equipped officers with CEDs
and were sometimes used at
rates that exceeded emptyhand control. Unlike pepper
spray, CEDs do not require
decontamination and do not
carry the risk of accidental
“blow back” that often oc­
curs with pepper spray use.
However, they do entail the
removal of prongs and the
potential for an unintended
shock to an officer. Even
with these concerns, they
are rapidly overtaking other
force alternatives. Although
the injury findings suggest
that substituting CEDs for
physical control tactics may
be useful, their ease of use
and popularity among officers
raise the specter of overuse.

I

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The possible overuse of
CEDs has several dimen­
sions. CEDs can be used
inappropriately at low levels
of suspect resistance. Law
enforcement executives can
manage this problem with
policies, training, monitoring
and accountability systems
that provide clear guidance
(and consequences) to of­
ficers regarding when and
under what circumstances
CEDs should be used, or
when they should not be
used.
Besides setting the resis­
tance threshold appropriately,
good policies and training
would require that officers
evaluate the age, size,
gender, apparent physical ca­
pabilities and health concerns
of a suspect. In addition,
policies and training should
prohibit CED use in the pres­
ence of flammable liquids or
in circumstances where fall­
ing would pose unreasonable
risks to the suspect (in el­
evated areas, adjacent to traf­
fic, etc.). Policies and training
should address the use of
CEDs on suspects who are
controlled (e.g., handcuffed
or otherwise restrained) and
should either prohibit such
use outright or limit them to
clearly defined, aggravated
circumstances.

15

RESEARCH IN BRIEF / MAy 2011

In addition to being used too
often, CEDs can be used too
much. Deaths associated
with CED use often involve
multiple Taser activations
(more than one Taser at a
time) or multiple five-second
cycles from a single Taser.
CED policies should require
officers to assess continued
resistance after each stan­
dard cycle and should limit
use to no more than three
standard cycles. Follow­
ing CED deployment, the
suspect should be carefully
observed for signs of distress
and should be medically
evaluated at the earliest
opportunity.

Directions for future
research
CEDs can be used too much
and too often. A critical re­
search question focuses
on the possibility of officers
becoming too reliant on CEDs.
During interviews with officers
and trainers, the researchers
heard comments that hinted
at a “lazy cop” syndrome.
Some officers may turn to a
CED too early in an encounter
and may relying on a CED
rather than rely on the offi­
cer’s conflict resolution skills
or even necessary hands-on
applications. Research should
explore how officers who
have CEDs perceive threats,
16

compared to officers who do
not have them. In addition,
it is important to determine
when, during an encounter,
an officer deploys the CED.
Another important CEDrelated research project
would be a case study of
in-custody deaths involv­
ing CED use and a matched
sample of in-custody deaths
when no CED use occurred.
Advocacy groups argue that
CEDs can cause or contrib­
ute to suspect deaths. The
subjects in CED experimen­
tal settings have all been
healthy people in relatively
good physical condition who
are not under the influence
of alcohol or drugs. There
is no ethical way to expose
overweight suspects who
have been fighting or using
drugs to the effects of CEDs,
so an examination of cases
where similar subjects lived
and died may shed some
light on the reasons for the
deaths. Law enforcement
officials typically argue that
most if not all the subjects
who died when shocked by
a CED would have died if
the officers had controlled
and arrested them in a more
traditional hands-on fight.
At this point, the argument
is rhetorical and research is
needed to understand the
differences and similarities in
cases where suspects died

PolICE USE oF FoRCE

in police custody, including
deaths where a CED may or
may not have been involved.
Finally, female officers in
Seattle were more than twice
as likely to suffer injuries as
males. Perhaps the finding
in Seattle is an anomaly, but
it should be investigated
further.

Notes
1. Police Executive Research Forum,
“Comparing Safety Outcomes
in Police Use-of-Force Cases for
Law Enforcement Agencies That
Have Deployed Conducted Energy
Devices and a Matched Comparison
Group That Have Not: A QuasiExperimental Evaluation,” report
submitted to the National Institute
of Justice, grant number 2006-IJ­
CX-0028, 2009: 13.
2. http://www.ojp.usdoj.gov/nij/
topics/technology/less-lethal/
how-ceds-work.htm.
3. Ibid.
4. http://www.ojp.usdoj.gov/nij/
topics/technology/less-lethal/
monitoring-ced-use.htm.
5. Edwards, S.M., J. Granfield, and J.
Onnen, Evaluation of Pepper Spray,
Research in Brief, Washington, D.C.:
U.S. Department of Justice, National
Institute of Justice, February 1997,
NCJ 162358; Granfield, J., J. Onnen,
and C.S. Petty, Pepper Spray and
In-Custody Deaths, Alexandria, Va.:
International Association of Chiefs of
Police, 1994; Petty, C.S., “Deaths in
Police Confrontations When Oleores­
in Capsicum Is Used,” final report,

I

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Washington, D.C.: U.S. Department
of Justice, National Institute of Jus­
tice, 2004, NCJ 204029.
6. Henriquez, M., “IACP National
Database Project on Police Use of
Force,” in Use of Force by Police:
Overview of National and Local Data,
Washington, D.C.: U.S. Department
of Justice, National Institute of
Justice and Bureau of Justice Sta­
tistics, 1999: 19-24; Kaminski, R., C.
DiGiovanni, and R. Downs, “The Use
of Force Between the Police and
Persons With Impaired Judgment,”
Police Quarterly, 7 (2004): 311-338;
Smith, M.R., and M. Petrocelli,
“The Effectiveness of Force Used
by Police in Making Arrests,” Police
Practice and Research, 3 (2002):
201-215.
7. Alpert, G.P., and R.G. Dunham,
“Analysis of Police Use-of-Force
Data,” final report, Washington,
D.C.: U.S. Department of Justice,
National Institute of Justice, 2000,
NCJ 183648; Alpert, G.P., and R.G.
Dunham, Understanding Police Use
of Force: Officers, Suspects, and
Reciprocity, Cambridge, NY: Cam­
bridge University Press, 2004; Ka­
minski, R.J., and D.W.M. Sorensen,
“A Multivariate Analysis of Indi­
vidual, Situational, and Environmen­
tal Factors Associated with Police
Assault Injuries,” American Journal
of Police, 14 (3/4) (1995): 3-48.
8. See, e.g., Alpert and Dunham,
2000, note 7.
9. Granfield, Onnen, and Petty, 1994,
note 5; Petty, 2004, note 5.
10. Edwards, Granfield, and Onnen,
1997, note 5; Kaminski, R.J., S.M.
Edwards, and J.W. Johnson, “As­
sessing the Incapacitative Effects
of Pepper Spray During Resistive
Encounters With the Police,”

17

RESEARCH IN BRIEF / MAy 2011

Policing: An International Journal of
Police Strategies and Management,
22 (1999): 7-29; Lumb, R.C., and
P.C. Friday, “Impact of Pepper Spray
Availability on Police Officer Use­
of-Force Decisions,” Policing: An
International Journal of Police Strate­
gies and Management, 20 (1997):
136-148; National Institute of Jus­
tice, The Effectiveness and Safety of
Pepper Spray, Research for Practice,
Washington, D.C.: U.S. Department
of Justice, National Institute of Jus­
tice, 2003, NCJ 195739; Nowicki, E.,
“Oleoresin Capsicum: A Non-Lethal
Force Alternative,” Law Enforce­
ment Technology, 20 (1993): 24-27;
Smith and Petrocelli, 2002, note 6.
11. Charlotte-Mecklenburg Police
Department, Taser Project: First
Year—Full Deployment Study. Char­
lotte, N.C.: Charlotte-Mecklenburg
Police Department, 2006; Hougland,
S., C. Mesloh, and M. Henych, “Use
of Force, Civil Litigation, and the
Taser,” FBI Law Enforcement Bul­
letin, 74 (2005): 24-30; Jenkinson, E.,
C. Neeson, and A. Bleetman, “The
Relative Risk of Police Use-of-Force
Options: Evaluating the Potential for
Deployment of Electronic Weap­
onry,” Journal of Clinical Forensic
Medicine, 13 (2005): 229-241.
12. Dennis, A.J., D.J. Valentino, R.J.
Walter, K.K. Nagy, J. Winners, F.
Bokhari, D.E. Wiley, K.T. Joseph,
and R.R. Roberts, “Acute Effects of
TASER X26 Discharges in a Swine
Model,” The Journal of Trauma,
Injury, Infection and Critical Care,
63 (2007): 581-590; Esquivel, A.,
E. Dawe, J. Sala-Mercado, R. Ham­
mond, and C. Bir, “The Physiological
Effects of a Conducted Electri­
cal Weapon in Swine,” Annals of
Emergency Medicine, 50 (2007):
576-583; Ho, J.D., J.R. Miner, D.R.
Lakireddy, L.L. Bultman, and W.G.

18

Heegaard, “Cardiovascular and
Physiologic Effects of Conducted
Electrical Weapon Discharge in Rest­
ing Adults,” Academic Emergency
Medicine, 13 (2006): 589-595; Lak­
kireddy, D., D. Wallick, A. Verma,
K. Ryschon, W. Kowalewski, O.
Wazni, J. Butany, D. Martin, and P.J.
Tchou, “Cardiac Effects of Electrical
Stun Guns: Does Position of Barbs
Contact Make a Difference?” Pacing
and Clinical Electrophysiology, 31
(2008): 398-408; McDaniel, W.C.,
R.A. Stratbucker, M. Nerheim, and
J.E. Brewer, “Cardiac Safety of Neu­
romuscular Incapacitating Defensive
Devices,” Pacing and Clinical Elec­
trophysiology, 28 (2005): s284-s287;
Nanthakumar, K., I.M. Billingsley, S.
Masse, P. Dorian, D. Cameron, V.S.
Chauhan, E. Downar, and E. Sevapt­
sidis, “Cardiac Electrophysiological
Consequences of Neuromuscular
Incapacitating Device Discharges,”
Journal of the American College of
Cardiology, 48 (2006): 798-804; Roy,
O.Z., and A.S. Podgorski, “Tests
on a Shocking Device — The Stun
Gun,” Medical and Biological Engi­
neering and Computing, 27 (1989):
445-448; Stratbucker, R., R. Roeder,
and M. Nerheim, “Cardiac Safety of
High Voltage Taser X26 Waveform,”
Engineering in Medicine and Biology
Society, Proceedings of the 25th
Annual International Conference of
the IEEE EMBS, Cancun, Mexico,
1094-678X, 4 (2003): 3261-3262;
Walter, R., A. Dennis, D. Valentina,
B. Margeta, K. Nagy, F. Bokhari, D.
Wiley, K. Joseph, and R. Roberts,
“TASER X26 Discharges in Swine
Produce Potentially Fatal Ventricular
Arrhythmias,” Academic Emergency
Medicine, 15 (2008): 66-73.
13. Dawes, D.M., J.D. Ho, M.A.
Johnson, E. Lundin, T.A. Janchar,
and J.R. Miner, “15-Second Con­
ducted Electrical Weapon Exposure

PolICE USE oF FoRCE

Does Not Cause Core Body Tempera­
ture Elevation in Non-Environmentally
Stressed Resting Adults,” Forensic
Science International, 176 (2008):
253-257; Dawes, D.M., J.D. Ho, and
J.R. Miner, “The Effect of a CrossChest Electronic Control Device
Exposure on Breathing,” Annals of
Emergency Medicine, 54 (2008):
65; Dawes, D.M., J.D. Ho, M.A.
Johnson, E. Lundin, and J.R. Miner,
“15-second Conducted Electri­
cal Weapon Application Does Not
Impair Basic Respiratory Parameters,
Venous Blood Gases, or Blood
Chemistries and Does Not Increase
Core Body Temperature,” Annals
of Emergency Medicine, 50 (2007):
6; Dawes, D.M., J.D. Ho, M.A.
Johnson, E. Lundin, and J.R. Miner,
“Breathing Parameters, Venous
Blood Gases, and Serum Chem­
istries With Exposure to a New Wire­
less Projectile Conducted Electrical
Weapon in Human Volunteers,”
Annals of Emergency Medicine, 50
(2007): 133; Ho, J.D., D.M. Dawes,
L.L. Bultman, J.L. Thacker, L.D.
Skinner, J.M. Bahr, M.A. Johnson,
and J.R. Miner, “Respiratory Effect
of Prolonged Electrical Weapon
Application on Human Volunteers,”
Academic Emergency Medicine 14
(3) (2007): 197-201; Ho, J.D., J.R.
Miner, D.R. Lakireddy, L.L. Bultman,
and W.G. Heegaard, “Cardiovascular
and Physiologic Effects of Con­
ducted Electrical Weapon Discharge
in Resting Adults,” Academic
Emergency Medicine, 13 (2007):
589-595; Ho, J.D., D.M. Dawes,
R.F. Reardon, A.L. Lapine, and J.R.
Miner, “Echocardiographic Deter­
mination of Cardiac Rhythm During
Trans-Thoracic Wireless Conducted
Electrical Weapon Exposure,” An­
nals of Emergency Medicine, 52

I

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(2008): 62; Levine, S.D., C. Sloane,
T.C. Chan, J. Dunford, and G. Vilke,
“Cardiac Monitoring of Human Sub­
jects Exposed to the Taser,” Journal
of Emergency Medicine, 13 (2007):
47; Levine, S.D., C. Sloane, T.C.
Chan, G. Vilke, and J. Dunford, “Car­
diac Monitoring of Subjects Exposed
to the Taser,” Academic Emer­
gency Medicine, 12 (2005): 71; Vilke,
G.M., C. Sloane, K.D. Bouton, F.W.
Kolkhorst, S. Levine, T. Neuman, E.
Castillo, and T.C. Chan, “Physiologi­
cal Effects of a Conducted Electri­
cal Weapon on Human Subjects,”
Annals of Emergency Medicine, 26
(2007): 1-4.
14. National Institute of Justice,
Study of Deaths Following Electro
Muscular Disruption, Special Report,
Washington, D.C.: U.S. Department
of Justice, National Institute of Jus­
tice, 2011: 3, NCJ 233432.
15. Ibid., 4.
16. Ibid.
17. Ibid., 5.
18. The MDPD provides police
services to the unincorporated areas
of Miami-Dade County, Fla., which
together contain more than 1 million
people in a 1,840 square mile area.
19. The agencies included police
and sheriff’s departments in Austin,
Texas; Cincinnati, Ohio; Harris
County, Texas; Hillsborough County,
Fla.; Los Angeles (both the city and
the county); Miami-Dade, Fla.; Nash­
ville, Tenn.; Orlando, Fla.; Richland
County, S.C.; San Antonio, Texas;
and Seattle, Wash.

19

About the National Institute of Justice
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