The NYPD’s pilot body-camera program is set to launch tomorrow in three precincts across the city. Advocates of outfitting police officers with body cameras hope, among other things, that the devices will discourage officers from mistreating the public–and cause citizens to behave a little more politely toward cops, as well.

There are a number of reasons (including privacy concerns) why some people are worried about police body cameras. There are also a number of reasons why many people are dubious about the devices’ ability to help improve relations between the public and law enforcement. Cops have to turn body cameras on for them to work–though officers are supposed to turn them on during a number of specific scenarios, like when they stop a vehicle or arrest a suspect. And a lot of people wonder if the threat of video evidence will really deter cops from bad behavior in the heat of the moment–especially since bystander video of Staten Island resident Eric Garner’s death after being restrained in a chokehold by New York City police officers failed to result in an indictment.

There is some evidence to suggest that body cameras may indeed reduce cops’ use of force against citizens–and the number of complaints those citizens make against cops. But it’s probably too soon to make that pronouncement. The Atlantic spoke to Barak Ariel, a University of Cambridge criminologist who co-authored a study on the use of body cameras in Rialto, California:

…he found that police officers who weren’t wearing cameras were twice as likely to use force as those who were. During the 12-month experiment, the police department also saw a reduction in citizens’ complaints compared with previous years. The researchers concluded that the benefits of wearing cameras trumped the costs. But Ariel insists that there isn’t enough evidence so far to generalize the finding and assert that body-worn cameras offer a net benefit to community policing. The Rialto report, for example, was the world’s first randomized-controlled trial involving the technology.

As for the camera itself, we dug into the details of the Vievu LE3 a while back on Co.Labs—here’s how the cameras are used by police:

As police generate recordings throughout the day, videos are stored locally on the devices until the officers return to headquarters and download the files into their department’s database. At the end of a shift with a Vievu LE3 camera, an officer removes her camera and connects it to a computer with a USB cable. Using Vievu’s accompanying proprietary software, the officer then transfers the videos into their department’s system and write up notes on events from the day.

The devices keep a record of every time someone accesses the file. The files are encrypted; even the camera company can’t access them unless the NYPD grants permission. According to Vievu President Steve Lovell, the cameras include a feature called “Vidlock,” which ensures that once a camera has been assigned to a server and database, video recorded on that device can only upload to that server and database. This means cops can’t just hook their body cameras up to any old laptop with a USB cable and transfer files.

cops can’t just hook their body cameras up to any old laptop with a USB cable and transfer files

For his part, NYPD Commissioner William Bratton is enthusiastic about the program. “I’m very supportive of body cams,” he told CBS This Morning earlier this week. “I’m very excited personally about that.”

“I’m a great supporter of technology in policing,” he added. “I think it will eliminate a lot of the he said, she said situations where we don’t have video, and that will be a good thing.”