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How Do Body-Worn Cameras Affect the Amount and Makeup of Police-Initiated Activities? A Randomized Controlled Trial in Milwaukee, Wisconsin

NCJ Number
Journal of Experimental Criminology Volume: 16 Dated: 2020 Pages: 481-503
Daniel S. Lawrence; Bruce E. Peterson
Date Published
23 pages

This study examined how the amount and characteristics of police-initiated activities changed after the introduction of body-worn cameras (BWCs).


From May 21 to November 22, 2016, patrol officers and sergeants from the Milwaukee Police Department were involved in a randomized controlled trial. Through a stratified random sampling procedure, half the officers (n = 252) were assigned BWCs, while officers from the control group (n = 252) continued business as usual. The counts of proactive activities, which included a total count of self-initiated events, as well as traffic stops, business checks, subject stops, and park and walks, were examined using random-effects negative binominal panel regression analyses. The models included a unique measure of contamination to assess its impact on officers' proactivity. The study found that BWCs had no impact on the total amount of officer-initiated activities, traffic stops, or business checks. Officers with BWCs conducted approximately 8 percent fewer subject stops and 23 percent more park and walks than those in the control group. In all models, contamination levels were significantly, positively associated with the number of proactive activities that were conducted; however, the size of this effect was small. These findings suggest that BWC-wearing officers may be less likely to engage in proactive activities that are highly discretionary and that could potentially lead to confrontations with community members. As departments continue to develop BWC programs or fine-tune their existing BWC policies, more research is needed to understand the degree to which BWCs affect officers' behaviors and interactions with the public. 7 tables, 2 figures, and 38 references (publisher abstract modified)