A Big Test of Police Body Cameras Defies Expectations

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Until now, the most commonly cited study on police body cameras had suggested that cameras did indeed have a calming effect. That experiment took place in 2012 in Rialto, Calif., where officers were randomly assigned cameras based on their shifts. Over a year, shifts that included cameras experienced half as many use-of-force incidents (including the use of a police baton, Taser or gun) as those shifts without cameras. The number of complaints filed by civilians against officers also declined — a stunning 90 percent compared with the previous year.


A large study found police body cameras did not greatly alter behavior. In this model, a red light indicates the camera is recording. Credit Axon

The Rialto study had a big impact in policing. Axon (formerly known as Taser International) has sold more than 300,000 police cameras worldwide and cites the Rialto study on its website. A federal district judge also cited the study in 2013 when she ordered the New York City Police Department to conduct a yearlong pilot program using body cameras. (Results are due out this spring.)

But the Rialto experiment featured just 54 officers, compared with over 2,000 in Washington. Officers in Washington captured five times as many hours of video. The larger sample size and the long-term way the cameras were assigned added to the reliability of the D.C. results.

“This is the most important empirical study on the impact of police body-worn cameras to date,” said Harlan Yu from Upturn, a Washington, D.C., nonprofit consulting company that studies how technology affects social issues. It was not directly involved in the research. “The results call into question whether police departments should be adopting body-worn cameras, given their high cost.”

The federal government has given police departments more than $40 million to invest in body cameras, and state and local authorities have spent many millions more. The devices vary in price, but the biggest expense is the data-storage cost. In Washington, M.P.D. officers collect about a thousand hours of footage a day. About 40 percent of it is deleted within 90 days, while the rest is to be kept for months, years or decades, depending on the statute of limitations for the charges connected to the footage.

The cameras also have a cost in terms of privacy violations. In a report on the policies governing police body cams in 50 major departments, Upturn and the Leadership Conference on Civil and Human Rights found that many cities have weak rules in place. Those rules can allow departments to refuse to share footage with civilians who want to file complaints, for example.

Some companies are exploring ways to integrate facial recognition software into police cameras, a level of surveillance that would disproportionately affect low-income minority communities, where the police tend to spend the most time.

“D.C. has relatively strong body-worn-camera procedures,” Mr. Yu said. “In cities that have weaker policies, it’s certainly possible that the cameras may be doing more harm than good.” Like other advocacy groups, the A.C.L.U. has supported body cameras. But the study, says Monica Hopkins-Maxwell at the A.C.L.U. of D.C., “should give us pause.”

Thousands of officers wear cameras now, but what they reveal and hide may surprise you.

For now, Washington officials say they intend to continue using cameras. But they admit to being surprised by the findings.

“I thought it would make a difference on police and civilian behavior — particularly for officers, and this is the exception, who might be more inclined to misbehave,” said the M.P.D. chief, Peter Newsham.

Why didn’t the cameras change behavior? After all, we know that other cameras do change behavior. Public closed-circuit TV cameras seem to lead to a moderate decrease in crime, particularly in parking garages. Traffic cameras significantly decrease speeding and fatal accidents.

Even the suggestion that someone is watching us tends to influence us: In 2011, researchers at Newcastle University in England posted pictures of a pair of male eyes and the caption, “Cycle Thieves: We Are Watching You.” Bike thefts decreased by 62 percent in those locations — and not elsewhere.

One hypothesis is that officers got used to the cameras and became desensitized to them. But the researchers saw no difference in behavior during the initial phase, when the cameras were new. (The researchers also checked the data to make sure officers were turning their cameras on when they were supposed to, and found a very high level of compliance.) Another possibility is that officers without cameras were acting like officers with cameras, simply because they knew other officers had the devices.

An equally plausible explanation has to do with fear: In Washington, police officers are instructed to turn on their cameras whenever they answer a call or encounter the public in a law-enforcement context. The kinds of situations that might lead to civilian complaints or use-of-force incidents are high-stress encounters. When frightened, humans tend to act on automatic fear responses (or, in the case of good police officers in an ideal world, training).

“It’s a lot to ask, psychologically speaking, to not only remember the camera is on but to moderate your behavior,” said Mr. Yokum, the head of the Lab @ DC.


The Washington, D.C., police chief, Peter Newsham, shown earlier this month, said he still believed that body cameras improved trust with the community. Credit Carolyn Kaster/Associated Press

Finally, cameras may have had less impact in Washington, D.C., because the police department there has already had to confront excessive-force problems. After a devastating 1998 Washington Post series revealed that the city’s police department had shot and killed more people per resident in the 1990s than any other police force in a large American city, the Department of Justice entered into a memorandum of agreement with D.C. to reform its policing.

“We went through a transformation with regard to use of force when Justice came in here,” Chief Newsham said.

Cities that lack such accountability in their police culture may find cameras more effective, under this theory. (The Rialto Police Department had been reeling from a series of scandals when the Rialto study showed a large impact from cameras.)

Even if cameras do not reduce violent encounters, they can still offer other kinds of benefits: for training, or to hold a rogue officer accountable after the fact.

To Chief Newsham, the cameras’ primary benefit is to improve relations with the community. “The transparency and trust that the community has, knowing your department is recording the interactions, I don’t think you can undervalue that,” he said. So far, it’s hard to say for sure if cameras increase trust, but Chief Newsham said he’d like to find out more through additional studies like this one.

The nine-person research team pre-published its design online, so that there would be less temptation to rejigger the approach after the results were in (an emerging best practice in social science research).

“We like to be very anecdotal in policing — to compare this year to that year,” said M.P.D. Commander Ralph Ennis, who oversaw the rollout of the cameras and worked closely with researchers. “This study is a whole other thing.”

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