科学美国人60秒 SSS Police Body Cameras Appear to Moderate Interactions with Civilians

（单词翻译）

The last few years have seen numerous widely publicized incidents of civilians², black men in particular, being killed by police. In response, many officers are now required to wear body cameras. The theory is that technology will lessen³ the likelihood of an officer using unnecessary force to diffuse⁴ a situation. Now research finds that body cameras do indeed appear to keep encounters between police and civilians from intensifying⁵ to the point where a civilian¹ files a complaint–in a few jurisdictions⁶, anyway.  

The study is in the journal Criminal Justice and Behavior. [Barak Ariel et al., “Contagious Accountability”: A Global Multisite Randomized Controlled Trial on the Effect of Police Body-Worn Cameras on Citizens’ Complaints Against the Police]

Researchers collected data from seven police departments in the U.K. and the U.S. that serve a total population of two million people. The data represented over 1.4 million hours logged by nearly 2,000 police officers in 2014 and 2015.

Officers were randomly⁷ assigned to either wear or not wear body cameras week by week. When the police wore the cameras they were required to have them on at all times.

The year before the study, a total of 1,539 complaints were filed against officers at the seven sites. But during the course of the body camera experiment, a total of just 113 complaints were filed—a reduction of 93 percent. Six of the seven sites saw complaint reductions of at least 88 percent.   

An interesting finding was that complaints against officers wearing body cameras were almost equal to complaints against those who were not wearing the cameras. The study’s authors suggest that the change in police behavior from wearing the camera continued even after the camera was removed. This effect is called “contagious accountability”: all officers became more conscious of their actions—camera or no camera.

—Erika Beras

[The above text is a transcript⁸ of this podcast.]