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

By ·November 17, 2017
University of Virginia

The Issue:

Public outrage following several high profile police shootings captured on cell phone videos led police departments across the nation to equip officers with body cameras. The policy aimed to improve transparency and accountability, in the hopes of reducing the use of force by police officers and thereby increase communities’ trust in those paid to serve and protect them. But, are body-worn cameras the solution they’re hoping for? The current research evidence is mixed.

In spite of the attention on these cameras, there are many issues that have yet to be resolved regarding their implementation and, importantly, their impact.

The Facts:

  • Local police agencies in many major cities and counties are either considering or implementing programs that equip police officers with body-worn cameras (BWCs). The cameras are typically designed to be located on an officer's chest or head and are equipped with a microphone and internal data storage that allows audio and video footage to be stored and analyzed. The U.S. Department of Justice has provided federal funds to support the establishment of body-worn camera programs at the local level. In spite of the policy focus on these cameras, there are many issues that have yet to be resolved regarding their implementation (see here for a survey of agencies) and, importantly, their impact.
  • Body-worn camera programs are extremely costly, mostly due to the costs of storing and managing the video footage. For instance, Washington DC — which has conducted one of the largest program rollouts so far — spent $1 million dollars on cameras, and will spend an additional $2 million each year for storage going forward. Implementing BWCs therefore has large opportunity costs, as the city could have spent that money on other programs that could have bigger benefits.
  • In theory, the use of cameras could reduce the use of force because cameras could have a civilizing effect on all involved. Officers and civilians alike should behave better when they know their behavior is being recorded, reducing the number of violent interactions between officers and civilians. In cases where officers do use force, the video footage will offer factual evidence about what occurred, so that abusive officers can be quickly disciplined, fired, or even convicted of crimes, preventing them from further abusive use of force. If BWCs have either of these effects, use of force by police should fall.
  • But, police cameras could also have little additional impact on police behavior and community interactions. Cameras are already so ubiquitous due to the widespread use of cell phone cameras and close-circuit television cameras that officers and civilians may already assume they are being recorded at all times.
  • It’s also possible that having police officers wear cameras could increase use of force. Perhaps most officers show restraint in heated situations to avoid being accused of bad behavior. You might think this implausible, given how rare it is for police officers to face disciplinary action. But facing an accusation can be quite unpleasant, even if it does not lead to penalties, and even a small chance of losing your job or going to prison might be enough to make at least some police officers wary of using force in a borderline situation. Those officers may become more likely to use force when they know camera footage will demonstrate the facts were on their side.
  • Since the effect of body-worn cameras could be positive or negative or zero, we need to rigorously test the effects to know how people respond to this tool. In order to determine whether any change in police encounters is caused by the presence of the cameras, researchers need to be able to compare the behavior of officers who are wearing cameras with the behavior of a control group that isn’t wearing them and are operating under very similar circumstances. A variety of American and European police departments have implemented body-worn cameras in so-called randomized controlled trials (RCTs), which allow this type of analysis. They randomly assign when officers are supposed to wear a camera and when they’re not. Most studies vary camera use by shift, so that everyone on duty at particular times wears a camera, and at other times everyone doesn’t. In a new study in Washington, DC, the police department randomized cameras by officer, so that some officers always wore a camera, while other officers never did.
  • Evidence on whether the cameras improved police behavior is so far mixed. The studies in American and European police departments found that body-worn cameras reduced the number of complaints filed by local residents against the police. However, they showed mixed effects on use of force by and against police officers. In some places, body-worn cameras increased the use of force, and in others they decreased the use of force.
  • The first large-scale study of the use of police cameras in a major U.S. city, Washington, DC, found that the behavior of officers who wore cameras all the time was indistinguishable from the behavior of those who never wore cameras. There was no significant difference on the use of force by officers or citizen complaints against officers that could be attributed to the use of cameras. It is possible that the behavior of police officers that were not wearing cameras was affected by the presence of officers who wore cameras (for instance, when a number of officers were together at the scene of a crime). But the rollout of BWCs did not affect the total amount of force used by police in the District, which you would expect if the cameras affected the behavior of both officers with cameras and those without. The authors looked at myriad other outcomes and found that BWCs had no significant effect on any of them. This was the first randomized control trial of body-worn cameras in a major U.S. city, and so will be of particular interest to other large cities rolling out this type of programs.
  • Improving police behavior isn’t the only potential benefit of body-worn cameras, and randomized control trials may not be able to fully capture these programs’ effects. It’s possible that body-worn cameras affect community trust in ways that don’t show up in police data: if individuals feel safer and trust the police more, that’s a good thing, even if actual use of force isn’t changing. Community trust could be measured by a survey, but researchers would need a different empirical strategy; a within-community randomized control trial cannot measure community-wide effects. Body-worn cameras could also provide video evidence in extreme cases where a problem officer needs to be held accountable, making justice easier to achieve. Assuming that such events are relatively rare, this benefit would be difficult to quantify using a study that lasts only a few months.

What this Means:

In trying to understand why results on the effectiveness of the use of body cameras by police have been mixed, the context surely matters – how severe is the local problem, how motivated are officers to change their behavior, and how much accountability do the cameras provide? Specific details also play a role. Local policies about when officers are required to turn their cameras on, and when footage is released, likely have an impact on the value of body-worn camera programs. Figuring out whether changing these policies can increase program effectiveness is a crucial next step in this research area. Police departments should be clear about what goals they are trying to achieve with their body-worn cameras, and how they will measure whether those programs are working as intended. Given the mixed results so far, places considering implementing body-worn cameras should rigorously evaluate their programs to be sure the local benefits are worth the costs.


Crime / Crime and Criminal Justice / Law Enforcement
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