Do Body-Worn Cameras Actually Reduce Police Use of Force?

Police departments, legislatures, and communities across the nation have been gripped by conversations about police use of force since the death of Michael Brown in Ferguson, Missouri in 2014. High-profile incidents, including the recent second-degree murder conviction of former Chicago Police Department officer Jason Van Dyke in the on-duty shooting death of 17-year-old Laquan McDonald, have kept questions surrounding use of force at the forefront of national conversations on public safety.

Body-worn cameras (BWCs) have been a touchstone in this discussion from the beginning. Since President Obama’s call for BWC funding in late 2014, hundreds of police departments have deployed BWCs as a way to improve community-police relations and interactions. Initially the evidence-based justification for BWCs was largely a study conducted in Rialto, California, which showed large decreases in both force incidents and civilian complaints. The theory behind BWCs is seemingly intuitive: When civilians and officers know they’re being recorded - that “someone is watching” - they behave better for the unseen audience. However, the actual evidence is not as straight-forward.

Studies find differing outcomes

Some more-recent studies also suggest that BWCs can help significantly reduce use of force incidents. In a study published in 2018, the Las Vegas Metropolitan Police Department partnered with an external research team to execute a randomized controlled trial of body cameras with volunteer participants. Participating officers were all required to complete BWC training, and some officers were selected to wear BWCs on patrol for an entire year. As expected, officers with BWCs used less force and received fewer complaints over that year.

The Las Vegas results are consistent with another recent study, this one from the Spokane Police Department in Washington. The Spokane police issued BWCs across their entire department in two phases, six months apart from each other. The trial revealed that both use-of-force and complaints against officers decreased six months post-BWC implementation, though similar reductions were not observed one year post-implementation.

The kicker? The Las Vegas officers who wore BWCs didn’t just use less force and receive fewer complaints; they also issued more citations and initiated more arrests. While greater enforcement might be a benefit, it’s perhaps not a result that early BWC advocates had in mind.

Further, not all studies on BWCs are drawing the same conclusions. Other departments have seen no observable results from the cameras. For example, a study performed when the Metropolitan Police Department of Washington, D.C. rolled out their body camera program across the entire department found that BWCs had no statistically significant impact on officer complaints or use of force. One multi-site, transnational randomized controlled trial led by Cambridge researcher Barak Ariel even found that officers wearing always-on cameras were, on average, assaulted more frequently than officers without cameras.

An important tool - but not a panacea

It is important to consider that additional studies over longer periods of time may reveal different results and clearer patterns. However, the differing findings in current studies would seem to illustrate an important point: BWCs are a tool, not a panacea. Like any tool, their use is context-dependent, suggesting BWCs might be an appropriate for addressing use of force in some communities or in some types of incidents, but perhaps not in others. Camera use has, for instance, been shown to decrease open-hand force, have no effect on heavier uses of force, and increase force against compliant subjects—all within the same department.

These differing studies demonstrate why we at the Policing Project feel so strongly that communities should first engage in cost-benefit analysis and develop clear policies before adopting new technology and tactics. A local benefit-cost analysis, conducted before assuming the massive cost of BWCs, can help lay any concerns bare and make sure the community knows what it’s signing up for.

Further, a benefit-cost analysis encourages policymakers to consider what complementary support might also help address the problem and prompts the police department to create comprehensive training protocols to accompany the technology. This last point is particularly crucial as having policies in place isn’t just a “best practice”— it’s key to achieving the right results. When the Cambridge research team controlled for officers’ compliance with BWC protocol in a subsequent analysis of their multi-site study, the increased assaults on officers went away.

At the least, if communities are adopting BWCs for reasons of accountability and transparency, they need policies in place that provide for release of footage when appropriate, either in response to complaints about officers, or after incidents like officer-involved shootings. The Policing Project was involved in crafting what became the Los Angeles Police Department’s video-release policy, which is now the law in the State of California. We suggest giving it a look.

This post was written by Policing Project externs David Drew, Kathleen Lewis and Alexia Ramirez.