Program Profile: Body-Worn Cameras to Reduce Use of Force by and Against Police in Eight Police Departments in the U.K. and U.S.

This is a police body-worm camera intervention that has been implemented across eight police departments in the United States and United Kingdom. The program equips officers with continuously recording body-worn cameras to record police and citizen interactions. The program is rated No Effects. There was no significant effect on police use of force, and use of cameras was associated with a statistically significant increase in assaults against officers.

A No Effects rating implies that implementing the program is unlikely to result in the intended outcome(s) and may result in a negative outcome(s).

This program's rating is based on evidence that includes at least one high-quality randomized controlled trial.

Program Goals /Target Sites

Police body-worn cameras, which police officers wear to record police and citizen interactions, are intended to reduce use of force by police and reduce complaints against the police. This may lead to other benefits, such as enhanced police legitimacy, professionalism, and transparency. In addition, the presence of body-worn cameras provides audio and video evidence of assaults against officers and therefore increases individual accountability, which may deter individuals from assaulting officers.

Program Components

A multisite study of police body-worn cameras was conducted in eight jurisdictions in the United Kingdom (i.e. West Midlands, Cambridgeshire, and Northern Ireland) and in the United States (i.e., Ventura and Rialto in California). All officers doing “camera on” shifts had to wear and keep the camera on during their entire shift (typically between 8 and 12 hours) and inform members of the public, during any encounter, that they were wearing a camera that was recording their interaction. Police officers did not have discretion about when cameras were to be turned on (except when officers were responding to specific types of incidents such as serious sexual assaults).

Program Theory

The use of body-worn cameras and their effects on reducing use of force and assaults on officers is rooted in deterrence theory. The certainty of detection or apprehension for wrongdoing is perceived to increase, and therefore decrease the incidence of such behavior. Thus, body-worn cameras should increase people’s perceptions of the risk of detection or apprehension because their actions will be caught on camera (this applies to the behavior of both suspects and police).

Study 1

Ariel and colleagues (2016) evaluated the impact of police-body worn cameras on officer use of force and assaults against officers. This is the first study to examine assaults against officers as an outcome measure for police body-worn cameras. The authors conducted a prospective meta-analysis of 10 randomized controlled trials involving 2,122 police officers from eight police departments. Two of the police forces covered two separate geographic areas that were included in the trial; this accounts for the greater number of trials than police forces. The eight police forces were located in the United States (Ventura and Rialto, California) and in the United Kingdom (West Midlands, Cambridgeshire, and Northern Ireland).

Each trial randomly assigned officer shifts to either treatment (with cameras) or control (no cameras) conditions on a weekly basis. Of a total of 4,915 shifts, 2,447 shifts were assigned to the treatment group, and 2,468 shifts were assigned to the control group. There were no differences between treatment and control conditions in terms of the distribution of shifts.

The outcomes included whether an officer used force during a shift (if so, how many times) and whether officers were assaulted (if so, how many times). These were standardized as rates per 1,000 per shift, because the police forces ranged in size. To mitigate differences in how ”force” was defined across the eight different sites, the analyses focused on any physical restraint beyond the use of verbal commands during an arrest (for example, if an officer used pepper spray). Assaults against police officers were self-reported based on routine reporting requirements.

The Comprehensive Meta-Analysis Version 2 software was used to synthesize the results from the trials and present the overall results, using standardized difference of means to compare treatment and control conditions across all sites. Subgroup analyses were conducted.

Subgroup Analysis

According to the study authors, the results were heterogeneous and appear to be driven by the 55 percent difference in the prevalence of use of force in treatment conditions, compared with the control conditions, in three studies. However, these results were countered by negative findings at most sites (i.e., use of force increased in treatment versus control shifts). Ariel and colleagues (2016a) stated, “These puzzling results flip the theoretical basis for the study on its head: there was no reason to suspect that the use of force by officers would increase when cameras were turned on, as these acts are virtually guaranteed to be caught on camera and should, thus, deter officers” (p. 750).

A subgroup analysis was conducted in a follow-up evaluation (Ariel et al. 2016b), which assessed to what extent officer compliance affected police use of force. When officers fully complied with the experimental protocol and did not use discretion (i.e., they kept their cameras on at all times), use of force rates were 37 percent lower for the treatment group than the comparison group. However, when officers did not comply with treatment protocol (i.e., chose when to turn cameras on/off), use of force rates were 71 percent higher for the treatment group than the comparison group. When full discretion was applied (i.e., either treatment group officers did not use cameras at all or control group officers used the cameras), there were no effects on police use of force.

These sources were used in the development of the program profile:

These sources were used in the development of the program profile:

Following are CrimeSolutions-rated programs that are related to this practice:

Body-Worn Cameras’ Effects on Police Officer Behavior

This practice involves the use of body-worn cameras by law enforcement. The aim of this practice is to record interactions from an officer’s point of view to improve accountability and positively affect police officer behavior. The practice is rated No Effects for its effects on officer use of force, officer injuries, officer-initiated calls for service, traffic stops, field interviews, and arrest incidents.

Evidence Ratings for Outcomes

	Justice Systems or Processes - Use of force
	Crime & Delinquency - Assault on officer/officer injuries/resistance
	Crime & Delinquency - Multiple crime/offense types
	Justice Systems or Processes - Officer-initiated calls for service
	Crime & Delinquency - Traffic stops/traffic tickets
	Justice Systems or Processes - Field interviews/stop and frisk

Why might a practice's outcome ratings differ from the ratings of specific programs encompassed by that practice?