Photo: JIM WATSON/AFP/Getty Images

As the U.S. continues to try to figure out how to improve cop-community relations, there’s more research suggesting that adding an unbiased, technological witness helps everyone involved. According to a new Cambridge University study of cops in Britain and California, adding body cameras lead to a staggering 93 percent drop in police complaints.

Reported on by Danny Shaw for the BBC, the study tracked about 2,000 cops in five U.K. regions and two California cities, accounting for 1.5 million hours of police work. The yearlong trial period saw 113 citizen complaints against police officers, a precipitous drop from the 1,539 of the previous year.

Lead author Barak Ariel told the BBC that the cameras led to greater accountability on the side of cops and drove down “disingenuous” complaints by the public. “I cannot think of any [other] single intervention in the history of policing that dramatically changed the way that officers behave, the way that suspects behave, and the way they interact with each other,” he said.

Just this week, the U.S. Department of Justice announced that it’s going to be giving $20 million to police departments in 32 states to fund body cameras. That’s about 13,000 cameras in total, Quartz reports, costing about $1,500 each with training and software.

A 2014 analysis of the effects of body cameras for the Phoenix Police Department found that they led to more arrests, fewer complaints, and more efficient court proceedings. Like the philosopher says, supervision changes behavior.