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Body Worn Camera

What Does the Science Say About Police Using Body-Worn Cameras?

A new systematic review by the Campbell Collaboration offers new insight into how BWCs work — and how they don’t.

Body-worn cameras have become nearly ubiquitous in law enforcement over the past decade, but there remains an unstated gap between expectations and reality. At the outset, activists and politicians often promoted BWCs as a panacea for a litany of challenges facing law enforcement, such as unnecessary use of force or discriminatory policing. Law enforcement leaders have emphasized the technology’s role in building accountability while also raising concerns about whether a camera would discourage vulnerable people from contacting law enforcement.

So what effect do BWCs actually have?

A new systematic, scientific synthesis of research on body-worn police cameras by the Campbell Collaboration, an international social science research network that produces high-quality evidence syntheses on issues relevant to public policy, set out to answer that question.

This kind of systematic review provides an in-depth and detailed review of existing literature and involves the use of robust methodology to find answers to a clearly formulated question. Overall this report involved thirty studies and covered 12 different types of outcome measures for officers or citizen behavior. This type of review is unprecedented in the realm of BWC research.

The report found that, despite being adopted by a majority of American law enforcement agencies, body-worn cameras do not have clear or consistent effects on officers or citizen behaviors. The use of BWCs does not seem to significantly affect officer arrests, use of force, tickets issued, stop-and-frisks, or other measured behaviors. The review, which was supported in part by Arnold Ventures, also found no consistent impact on citizen behavior during police interactions, such as the frequency of citizens resisting arrest or assaulting an officer.

However, the introduction of body-worn cameras did reduce the number of civilian complaints against officers. It is unclear whether this change is due to an improvement in police-citizen interactions or differences in people’s reporting habits. More research will be needed to explore whether BWCs improve police accountability or police-citizen relationships.

To discuss these interesting results, we talked with Howard White and Cynthia Lum. White is the CEO of The Campbell Collaboration. Lum is a professor of criminology and director of the Center for Evidence-Based Crime Policy at George Mason University.

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Arnold Ventures

Can you talk about what makes Campbell reviews distinctive?

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Howard White

The key thing on Campbell systematic reviews is the systematic element. It’s systematic in terms of defining the question, deciding which studies to include, what information to extract from those studies, how to analyze that information, and how to present that analysis. A traditional literature review is not systematic and is prone to many sorts of bias; the point of doing a systematic review is to try and minimize bias. For instance, many literature reviews are based on studies that appear in one or two databases, whereas a typical Campbell review will search a dozen databases, as well as seek out unpublished and ongoing research.

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Cynthia Lum

A Campbell review is a sharply focused meta-analysis of the most rigorous research out there. It tries to reduce the field to the most reliable studies that we have, in order to draw conclusions from them. Using meta-analysis also allows us to weight studies according to their rigor. Not only is the range of research stronger, but the results are more definitive. We also have the ability to describe the magnitude of findings, as opposed to just a yes or no.

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Arnold Ventures

Why did you decide to study body-worn cameras in the first place?

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Howard White

​The Campbell Collaboration's mission is to support the production of evidence synthesis of studies, and to have them taken up to inform policy. We work across a number of different sectors — crime and justice, education, a broad range of social welfare issues — but the sector most responsive to evidence is the criminal justice community, in particular the policing community. There’s been an evidence-based movement within police forces themselves. So we have been very keen to see the findings from this review as we feel there is a demand for the evidence about the effectiveness of body worn cameras.

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Cynthia Lum

Body-worn cameras are probably the most rapidly diffusing technology in policing. A large majority of police agencies in America have adopted body-worn cameras, and most police officers inside those agencies have body-worn cameras. The cost of that adoption is very high, in particular the maintenance of the cameras and the storage of video footage. I would also say that both people and police have very high expectations for the cameras. So this is an incredibly important intervention that we need to be studying. In terms of the cameras’ effects, does it actually deliver on the expectations that people and the police have for them given their costs?

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Arnold Ventures

The conclusion of this study is that the adoption of body-worn cameras doesn’t have clear or consistent effects on officers or civilian behavior, right?

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Cynthia Lum

Yes, except for one thing, which is that body-worn cameras seem to reduce complaints against officers. Police believe they reduce what they describe as frivolous complaints — minor complaints, or complaints that are unfounded. But they don’t seem to consistently or significantly affect officers’ use of force, stop and frisk, traffic stops, tickets, or other police and citizen activities.

There might be some circumstances under which cameras could be effective, such as what difference it makes if police have discretion when to turn the cameras off. There is some suggestion that less discretion makes cameras more effective, but we don’t have enough evidence to say that with confidence.

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Arnold Ventures

So the idea is that people are less likely to make a frivolous or minor complaint if they know that their behavior has been documented on camera.

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Cynthia Lum

Well, that is one theory. Early on in the use of cameras, there was some reporting about police agencies actually showing people video from the cameras. After seeing the footage, a person might be less inclined to file a complaint — even if it might be legitimate — if perhaps they felt they were also complicit or acting poorly.

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Arnold Ventures

I've read reports about police departments voluntarily adopting body-worn cameras for just this reason — they think it will prove that many of these complaints are false or frivolous.

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Cynthia Lum

Many police agencies believe that body-worn cameras will hold citizens accountable. And it's not really a secret — police leaders have said aloud and in public forums that they are adopting body-worn cameras for precisely that reason. Agencies believe that cameras can protect them as well.

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Arnold Ventures

How widespread are body-worn cameras in America and around the world?

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Cynthia Lum

Very widespread. The last Bureau of Justice Statistics assessment, which was back in 2016, showed that the majority of agencies in the U.S. had adopted them. My understanding is that all the forces in the U.K. have body-worn. They're becoming very common, at least in the UK, U.S., and Australia.

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Arnold Ventures

If I'm a police officer reading this report, I might think the money invested in body-worn cameras was worth it if they are cutting down on frivolous complaints. But if I'm a member of the public, I might wonder why we’re spending millions and millions of tax dollars on technology that isn’t doing what some people said it would do.

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Cynthia Lum

I don't think it's that simple on either the police or the citizen side. A citizen might say that if something bad happened to them or their family, they would want these officers to have body-worn cameras so at least it was documented. There’s also a great deal of uncertainty and speculation that drives decision-making about body-worn cameras. That’s the reality of criminal justice more generally — it’s why the U.S. has paid millions of dollars to support D.A.R.E. when we know it has very little any impact on youth drug use. Science and public policy aren’t always aligned. In this case, if you want technology to do what you want it to do, then the policing systems have to be in place that allow for that to happen. I think first-line supervisors can use body-worn camera footage like coaches use video, to correct officers’ everyday behavior. If citizens want body-worn cameras to be more effective, they have to demand more transparency from internal affairs. It's never just about the technology.

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Arnold Ventures

Looking at this report and beyond, what specific police reforms are needed to optimize the use of body-worn cameras?

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Howard White

The studies Cynthia looks at in this review asked what is called a first-generation question—do body-worn cameras work or not? The second-generation question would be about how different designs and implementation decisions affect effectiveness. An example is the point Cynthia made above about discretion moderating effectiveness. Hopefully, in three- or four-years’ time, there will be more studies and we can test the conditions which may make BWCs have more positive effects.

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Cynthia Lum

That’s the power of the Campbell Collaboration more generally. It's really about encouraging partnerships to generate stronger research. It's a continual conversation about building the evidence. That’s why we have to do continuous reviews. In five years we will have to update the body-worn camera review with the new research that has come out. The medical world is the same way. We see how COVID-19 is unfolding right now, where researchers are testing all these different therapeutics. It’s the same concept with the social sciences. There may be a therapeutic that we think is working today, but there may be something better tomorrow. The building of evidence is about what science is all about.