Police Use of Force: The Impact of Less-Lethal Weapons and Tactics
A new study suggests that less-lethal weapons decrease rates of officer and offender injuries.
In the mid-19th century, police officers in New York and Boston relied on less-lethal weapons, mostly wooden clubs. By the
late 1800s, police departments began issuing firearms to officers in response to better-armed criminals. Today, many law enforcement
agencies are again stressing the use of less-lethal weapons, but they are using devices that are decidedly more high-tech
than their 19th-century counterparts.
Use of force, including less-lethal weaponry, is nothing new to policing, and in any use-of-force incident, injury is a possibility.
Researchers have estimated that between 15 and 20 percent of arrests involve use of force. A group of researchers led by Geoffrey
P. Alpert, professor of criminology and criminal justice at the University of South Carolina, recently completed an NIJ-funded
study of injuries to officers and civilians during use-of-force events. Injury rates to civilians ranged from 17 to 64 percent
(depending on the agency reporting) in use-of-force events, while injury rates to officers ranged from 10 to 20 percent. Most
injuries involved minor bruises, strains and abrasions. Major injuries included dog bites, punctures, broken bones, internal
injuries and gunshot wounds.
Can New Technologies Decrease Injuries?
Advances in less-lethal technology offer the promise of more effective control over resistive suspects with fewer serious
injuries. Pepper spray was among the first of these newer, less-lethal weapons to achieve widespread adoption by police forces.
More recently, conducted energy devices (CEDs), such as the Taser, have become popular.
More than 11,000 American law enforcement agencies use CEDs, but their use has not been without controversy. Organizations
such as Amnesty International and the American Civil Liberties Union have questioned whether CEDs can be used safely, and
whether they contribute to civilian injuries and incustody deaths. Policymakers and law enforcement officials want to know
whether CEDs and other less-lethal weaponry are safe and effective, and how police should use them.
Analysis of Information from Specific Law Enforcement Agencies
Alpert's research on use of force and less-lethal weapons, in part, focused on data gathered from three law enforcement agencies
— the Richland County (S.C.) Sheriff's Department, the Miami-Dade (Fla.) Police Department and the Seattle Police Department.
Richland County Sheriff's Department
Approximately 475 sworn officers from the Richland County Sheriff's Department (RCSD) serve the unincorporated portions of
Richland County, S.C. The agency started phasing in Tasers in late 2004. During data collection, about 60 percent of deputies
Researchers coded 467 use-of-force reports from January 2005 to July 2006. The most frequent force level used by deputies
(59 percent of incidents) was soft empty hand control (e.g., holding a suspect to restrain him), which increased the odds
of officer injury by 160 percent.
Pepper spray decreased the odds of suspect injury by almost 70 percent, and a deputy aiming a gun at a suspect reduced his
or her injury odds by more than 80 percent (the act of pointing a gun alone often effectively ends a suspect's resistance).
The use of a canine posed, by far, the greatest injury risk to suspects, increasing injury odds almost fortyfold. Suspects
who displayed active aggression toward deputies were also more likely to suffer injuries.
In contrast to the Miami-Dade and Seattle Police Departments, Taser use by the RCSD had no effect on the likelihood of suspect
injury. Also in contrast to the Miami-Dade Police Department, Taser use by the RCSD had no effect on the likelihood of officer
injury; Taser use by the Seattle Police Department, however, similarly showed no effect on the likelihood of officer injury.
This suggests that not every agency's experience with CEDs will be the same.
Miami-Dade Police Department
With 3,000 officers, the Miami-Dade Police Department (MDPD) is the largest law enforcement agency in the southeast.
The MDPD started using Tasers in 2003. By May 2006, about 70 percent of the officers carried Tasers. The researchers examined
762 use-of-force incidents between January 2002 and May 2006. Most injuries were minor, and officers were substantially less
likely to be injured than suspects, with 17 percent of officers injured and 56 percent of suspects injured.
Use of both soft hand tactics and hard hand tactics (e.g., using kicks or punches to restrain a suspect) by officers more
than doubled the odds of officer injury. Hands-on tactics also increased the odds of injury to suspects, as did the use of
canines. Taser use, however, was associated with a reduction in the likelihood of both officer and suspect injury.
Seattle Police Department
The Seattle Police Department (SPD) has about 1,200 sworn officers. The agency started using Tasers in December 2000. The
SPD recorded 676 use-of-force incidents between December 2005 and October 2006. Suspects suffered injuries in 64 percent of
the incidents, while officers suffered 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
Taser use was associated with a 48 percent decrease in the odds of suspect injury in a use-of-force incident (it was not associated
with a significant change in the odds of officer injury). The use of physical force by officers increased the odds of officer
injury 258 percent. Not surprisingly, the odds of officer injury also increased when suspects resisted by using physical force
or when suspects used or threatened to use a weapon.
Combined Agency Analysis
The researchers conducted a combined analysis of use-of-force data from 12 large local law enforcement agencies (including
Miami-Dade, Seattle and Richland County). The large sample, representing more than 24,000 use-of-force incidents, allowed the researchers to use statistical techniques
to determine which variables were likely to affect injury rates. The use of physical force (e.g., hands, fists, feet) 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.
To see if the introduction of CEDs was associated with changes in injury rates in individual police departments, the researchers
reviewed monthly reports of use-of-force incidents and of officer and suspect injuries from police departments in Austin,
Texas, and Orlando, Fla., both before and after the introduction of CEDs.
The Orlando data included 4,222 incidents from 1998 to 2006 (CED use began in February 2003). The Austin data included 6,596
incidents from 2002 to 2006 (CED use was phased in beginning in 2003 and was completed in June 2004). Use-of-force cases increased
in Orlando after CEDs were deployed, but they dropped after full deployment of CEDs in Austin. A large drop in injury rates
for suspects and officers alike occurred in both cities following CED introduction.
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 fullscale Taser deployment.
In Orlando, the decline in officer injury rates was even greater than for suspects, with the average monthly rate dropping
by 60 percent after Taser adoption. In Austin, officer injuries dropped by 25 percent.
Interviews with Officers and Suspects
Researchers also collected qualitative data through interviews with officers and suspects involved in use-of-force incidents.
Researchers conducted interviews with 219 officers from the Richland County Sheriff's Department, 35 officers from the Columbia
(S.C.) Police Department (CPD) and 35 suspects involved in use-of-force situations. Unlike the RCSD, the CPD does not use
In nine incidents (out of 109), officers in the RCSD reported that a Taser did not work properly or did not have the desired
effect. Researchers received reports of multiple Taser hits on a suspect (i.e., more than one officer using a Taser on a single
suspect) and multiple uses of the Taser in drive stun mode (when the Taser is pressed against a suspect rather than firing
Nine percent of the officers reported injuries, almost all of which were scrapes, cuts or bruises suffered while struggling
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.
In 22 cases, researchers interviewed both the officers and the suspects involved in an incident. Suspects often told a different
story than the officer who arrested them. In almost all cases, suspects said officers used excessive force and that they were
not resisting. Some suspects said officers used Tasers early in the interaction, and several said the officers seemed to enjoy
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 Tasers on them after they were handcuffed.
Implications for Policy, Training and Future Research
CED use is widespread and often controversial. Based on their findings, the researchers involved in this study made recommendations
about whether and how CEDs should fit into the range of less-lethal force alternatives available to law enforcement officers.
If injury reduction is the primary goal, however, agencies that deploy pepper spray and CEDs are clearly at an advantage.
Both weapons prevent or minimize the physical struggles that are likely to injure officers and suspects alike.
The researchers compared injuries reported by the RCSD and by the CPD. Most injuries in both agencies occurred when officers
and suspects struggled on the ground, but the differences between the agencies in terms of percentage of officers and suspects
injured were striking. The RCSD deputies, most of whom carry Tasers, reported fewer injuries to themselves and suspects from
ground fighting than did CPD officers, who do not carry CEDs (9 percent and 31 percent, respectively). Injuries to suspects
caused by contact with the ground were also lower in RCSD incidents. Some of the injuries to CPD officers and suspects might
have been prevented had officers used CEDs instead of hands-on tactics.
Although both pepper spray and CEDs cause pain, they reduce injuries; and, according to current medical research, death or
serious harm associated with their use is rare. In that sense, both are safe and similarly effective at reducing injuries. The researchers recommend that both should be
allowed as possible responses to defensive or higher levels of suspect resistance. This recommendation is followed by most
agencies that responded to a national survey conducted by the Police Executive Research Forum.
Policy and Training Issues Related to CEDs
CEDs are rapidly overtaking other force alternatives. Although the injury findings suggest that substituting CEDs for physical
control tactics may decrease the chance of injury, their ease of use and popularity among officers raise concerns about overuse.
CEDs can be used inappropriately. Law enforcement executives can manage this problem with policies, training, monitoring and
accountability systems that provide clear guidance (and consequences) to officers regarding when and under what circumstances
CEDs should and should not be used.
Besides setting the resistance threshold appropriately (that is, determining the level of suspect resistance at which officers
should be allowed to use CEDs), good policies and training would require that officers evaluate the age, size, sex, apparent
physical capabilities and health concerns of a suspect. In addition, policies and training should prohibit CED use in the
presence of flammable liquids or in circumstances where falling would pose unreasonable risks to the suspect (e.g., in elevated
areas, adjacent to traffic, etc.). Policies and training should address use on suspects who are controlled (e.g., handcuffed
or otherwise restrained) and should either prohibit such use outright or limit it to clearly defined, aggravated circumstances.
In addition to the possibility of CEDs being used in too many cases (i.e., inappropriately in instances of low-level resistance),
there are also concerns about CEDs being used too many times in a single case. Deaths associated with CED use often involve
multiple CED activations (more than one CED at a time) or multiple five-second cycles from a single CED. CED policies should
require officers to assess continued resistance after each standard cycle and should limit use to no more than three standard
cycles. Following 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
A critical research question is whether officers can become 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 rely on a CED rather than on their conflict resolution skills or even on hands-on applications.
Another important CED-related research project would be a study of in-custody deaths involving CED use and a matched sample
of in-custody deaths when no CED use occurred. Advocacy groups argue that CEDs can cause or contribute to suspect deaths. The subjects in CED experimental settings have all been healthy people in relatively good physical condition who were not
under the influence of alcohol or drugs. However, not all subjects in actual cases of CED use would meet experimental requirements
of good health. Law enforcement officials typically argue that most, if not all, of the citizens who died when shocked by
a CED would have died if the officers had controlled and arrested them in a more traditional hands-on fashion. Research is
needed to understand the differences and similarities in cases where suspects died in police custody, including deaths where
a CED may or may not be involved.
The National Institute of Justice funded this study. Read the complete report (pdf, 173 pages).
NIJ Journal No. 267, Winter 2010
About the Author
Philip Bulman is a writer with the National Institute of Justice.
Back to the top.
For More Information
- Smith, M. R., R. J. Kaminski, G. P. Alpert, L. Fridell, J. MacDonald, and B. Kubu, A Multi-Method Evaluation of Police Use of Force Outcomes (pdf, 173 pages), Final report submitted to the National Institute of Justice, Washington, DC: National Institute of Justice, July 2010 (NCJ
- National Institute of Justice, Study of Deaths Following Electro Muscular Disruption: Interim Report (pdf, 21 pages), Washington, DC: National Institute of Justice, June 2008 (NCJ 222981).
 Note that more than one use-of-force tactic could be recorded for each incident.
 The other nine 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); Nashville, Tenn.; Orlando, Fla.; and San Antonio, Texas.
 For a more in-depth description of the researchers' approach to their longitudinal analysis, see section 6 of the report,
"A Multi-Method Evaluation of Police Use of Force Outcomes" (pdf, 173 pages).
 National Institute of Justice, Study of Deaths Following Electro Muscular Disruption: Interim Report (pdf, 21 pages), Washington, DC: National Institute of Justice, June 2008 (NCJ 222981).
 Details about the national survey can be found in section 3 of the report.
 Amnesty International, 'Less Than Lethal'? The Use of Stun Weapons in US Law Enforcement Exit Notice, London, England: Amnesty International Publications. 2008.
Date Created: March 3, 2011