No Effects - One study
Randomized Controlled Trial
Date: This profile was posted on July 10, 2018
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.
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.
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).
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).
Police Officer Use of Force
Ariel and colleagues (2016) found that across the randomized controlled trials conducted at eight different police departments, police body-worn cameras had no effect on police use of force, compared with the control group.
Assaults Against Officers
Police body-worn cameras were also associated with a statistically significant increase in assaults against officers. The rate of assaults against officers per 1,000 arrests was 14 percent higher when cameras were present.
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.
There is no cost information available for this program.
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.
Evidence-Base (Studies Reviewed)
These sources were used in the development of the program profile:Study 1
Ariel, Barak, Alex Sutherland, Darren Henstock, Josh Young, Paul Drover, Jayne Sykes, Simon Megicks, and Ryan Henderson. 2016a. “Wearing Body Cameras Increases Assaults Against Officers and Does Not Reduce Police Use of Force: Results from a Global Multi-Site Experiment.” European Journal of Criminology
These sources were used in the development of the program profile:
Ariel, Barak, Alex Sutherland, Darren Henstock, Josh Young, Paul Drover, Jayne Sykes, Simon Megicks, and Ryan Henderson. 2016b. “Report: Increases in Police Use of Force in the Presence of Body-Worn Cameras are Driven by Officer Discretion: A Protocol-Based Subgroup Analysis of Ten Randomized Experiments.” Journal of Experimental Criminology
Sherman, Lawrence W. 1990. “Police Crackdowns: Initial and Residual Deterrence.” Crime and Justice
University of Cambridge. Body-Worn Cameras Associated with Increased Assaults Against Police, and Increase in Use-Of-Force If Officers Choose When to Activate Cameras.
Cambridge, U.K.: University of Cambridge.https://www.cam.ac.uk/research/news/body-worn-cameras-associated-with-increased-assaults-against-police-and-increase-in-use-of-force-if