In View: BWCs and Their Ability to Reduce Complaints against Officers

Body-Worn Cameras Cause a Reduction of More Than 90% in Complaints against Police Officers


Dr. Barak Ariel, Jerry Lee Fellow in Experimental Criminology and Lecturer in Experimental Criminology, Institute of Criminology, University of Cambridge

A recent study published by the University of Cambridge, Hebrew University of Jerusalem, RAND, and several active-duty police officers in the journal Criminal Justice and Behavior suggests that equipping frontline officers with body-worn cameras (BWCs) could lead to dramatic reductions in citizens’ complaints filed against the police. The multisite randomized controlled trial showed that across seven experimental sites, complaints lodged against police officers dropped from 1,539 complaints in the 12 months preceding the study (roughly 220 complaints per site) to 113 (approximately 16 complaints per site) after introducing BWCs. This marks an overall reduction of 93 percent in the incidence of complaints. In some sites, the number of complaints went down to zero.

The study’s research design was straightforward, following the “Rialto experiment”: random assignment of police shifts into “camera shifts” and “no-camera shifts” to estimate the effect of BWCs on citizen complaints filed against police. Between 2014 and 2015, the research team studied thousands of these shifts, in different jurisdictions, in communities with thousands of residents (collectively more than 2 million citizens). Officers were asked to turn on the camera as soon as they began to engage with a member of the public, as well as to provide a verbal warning ahead of the engagement in order to “nudge” both parties into appropriate behavior for a recorded encounter. (On the role of discretionary powers in the use of BWCs, see the “IEEE Spectrum” article: “Do Police Body Cameras Really Work?”)

Notably, the before–after reductions in complaints were observed across all frontline officers in the participating departments, including during shifts when officers did not wear BWCs. The analyses comparing “camera shifts” versus “no-camera shifts” revealed only a 10-percent reduction in the odds of complaints being filed against officers. This reduction in complaints was observed across the entire department. Borrowing an analogy from the medical world, it seems that introducing BWCs has a transmittable impact: Officers modified their behavior regardless of wearing the BWC gear, once they were aware that they are being—or potentially can be—observed. BWCs seem to have a “contagious accountability” effect that spreads across the entire police department.

Ultimately, if complaints against the police are a proxy for police accountability, then BWCs can potentially be viewed as a tool for increasing police accountability in a dramatic way.  At the very least, accountability can be greatly enhanced, given the increased transparency of police actions. 

Barak Ariel is a lecturer in the Police Executive Programme. Among other topics, Barak provides seminars on research methods, systematic reviews and statistical analyses. As the chief analyst of the Jerry Lee Centre of Experimental Criminology, Barak is involved in several field experiments on police tactics in partnership with forces in the UK and abroad, including hotspot policing, restorative justice, use of cameras in police operations, informal crime control, and tax compliance.

This project was supported by Grant No. 2015-DE-BX-K002 awarded by the Bureau of Justice Assistance. The Bureau of Justice Assistance is a component of the Department of Justice's Office of Justice Programs, which also includes the Bureau of Justice Statistics, the National Institute of Justice, the Office of Juvenile Justiceand Delinquency Prevention, the Office for Victims of Crime, and the SMART Office. Points of view or opinions in this document are those of the author and do not necessarily represent the official position or policies of the U.S. Department of Justice.