Do Body-Cameras Increase Use of Force by Police and Assaults Against Officers?

Michael D. White, Ph.D., Arizona State University, BWC TTA Co-Director

Researchers from the University of Cambridge, RAND Europe, and their colleagues (Ariel et al. 2016a, 2016b) published two papers this week that explore this provocative question. The research designs employed are rigorous, the data are sound, and the results are intriguing. I applaud the researchers for making valuable contributions to the evidence base on body-worn cameras and their impact.

But let’s go back to the question posed: do BWCs increase use of force and assaults on officers? The answer is, in a word, “no.” There is no evidence from their research, or anywhere else, which demonstrates that BWCs cause officers to use force more frequently, or that BWCs cause citizens to be more aggressive toward officers. Now that we have addressed that question, let’s explore their studies in greater detail because the results are quite interesting.

On the use of force question, Ariel and colleagues (2016a: 2) find that, across 10 studies, BWCs “had no effect on use of force” overall, but the null finding is explained by mixed results across studies. In some sites, BWCs were associated with declines in use of force; in other sites, use of force actually increased during shifts where officers wore cameras (researchers randomized shifts rather than officers). The authors explore the inconsistent use of force findings in the second paper (Ariel et al., 2016b), and they link patterns in use of force to officer decisions on BWC activation. That is, when officers followed policy – they activated the BWC at the start of citizen encounters and advised the citizen of the BWC – use of force declined by 37%. When officers did not follow policy –that is, they did not consistently activate the BWC and did not make the citizen advisement –use of force actually increased by 71%. In sum, the presence of the BWC did not drive an increase in use of force. Rather, failure to follow policy and use the BWC as intended explains the increase in use of force. Ariel et al. (2016b: 2) conclude “BWCs ought to be switched on and the recording announced to suspects at early stages of police-public interactions.” I agree – the key takeaway message for police: during a formal law enforcement contact, activate the camera immediately and tell the citizen the encounter is being recorded. When officers do this, the evidence from this study and others is compelling that use of force rates will decline.

The question regarding assaults against officers is more difficult to interpret because, to my knowledge, the Ariel et al. (2016a) study is the first to examine this important outcome. The researchers do find that assaults on officers were more common during shifts where BWCs were present. Does this mean that BWCs are causing citizens to be more aggressive toward police? I don’t believe it – at least not on any widespread level. In fact, there are robust bodies of research in criminology and psychology that suggest the exact opposite should occur. Ariel et al. (2016b: 9) acknowledge that they cannot causally link BWCs to increased assaults on officers because “we cannot rule out alternative explanations at this stage.”

So why the increased assault rates? There are a few possibilities (Ariel and colleagues discuss them) but the explanation I find most compelling involves officer reporting. Simply put, officers may be more likely to report an assault against them now that the BWC can corroborate the claim. Before wearing BWCs, officers may have experienced low-level assaults (threatening statements, assaults resulting in no visible mark or injury) but routinely decided that the additional paperwork and hassle associated with reporting the assault is not worth the trouble. The BWC now changes that mindset. Video and audio from the BWC proves that the assault occurred and the officer feels both more confident and vindicated in making the formal report. As a result, increased reporting by officers generates an increase in recorded assaults.

I admit that the reporting effect is conjecture at this point. But it makes sense – and it makes more sense than the notion that BWCs are generating widespread aggression toward police officers. That said, the effect of BWCs on officer assaults is a new question, and it should be a top priority for researchers.

A few final thoughts on BWCs and their impact.

It should be clear now that not every police department rolling out BWCs is going to witness “Rialto-like” declines in use of force, citizen complaints, and other important outcomes (like assaults on officers). Drops of 50% in use of force and 90% in citizen complaints will never be the norm. And as the research evidence grows, it is becoming increasingly clear that there are optimal conditions for experiencing the positive effects of BWCs. For example, the studies discussed here highlight the importance of BWC activation as soon as possible during (or even before) formal law enforcement contacts, along with citizen advisement of the BWC.

The Bureau of Justice Assistance (BJA) National Body-Worn Camera Toolkit provides important information regarding other optimal conditions, including a thoughtful, collaborative planning process with internal and external stakeholders, detailed administrative policy, effective training, and continual program monitoring ( Moreover, agencies would be well-advised to stay current on the latest in research on BWCs (highlighted on the BJA Toolkit), and to take advantage of available resources and assistance though BJA’s BWC Pilot Implementation Program (

Last, we should think about what happens when BWCs are deployed in a high-functioning police department. By high-functioning, I mean a department that is professional, procedurally just (internally and externally), transparent, is legitimate in the eyes of the public, and which holds its officers accountable for their misdeeds and mistakes. Should we expect a 90% drop in citizen complaints in such a department? Should we expect a 50% drop in use of force in such a department?

In my opinion, the answer is no. The integration of BWCs into the daily routines of officers in this kind of department will be seamless, and there won’t be large drops in citizen complaints and officer use of force because there does not need to be. In such a department, the absence of declines in complaints and use of force won’t be a sign a failure – it will be a sign of success.

Michael D. White is a Professor in the School of Criminology and Criminal Justice at Arizona State University, and is Associate Director of ASU’s Center for Violence Prevention and Community Safety. He is also the Co-Director of Training and Technical Assistance for the Bureau of Justice Assistance Body-Worn Camera Pilot Implementation Program. He received his Ph.D. in Criminal Justice from Temple University in 1999. Prior to entering academia, Dr. White worked as a deputy sheriff in Pennsylvania.

References/Further Reading

  1. Ariel, B., Sutherland, A., Henstock, D., Young, J., Drover, P., Sykes, J., Magicks, S., & Henderson, R. (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, 1-12. DOI: 10.1177/1477370816643734.
  2. Ariel, B., Sutherland, A., Henstock, D., Young, J., Drover, P., Sykes, J., Megicks, S., & Henderson, R. (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, DOI 10.1007/s11292-016-9261-3
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