Do body cameras on police officers change policing or impact complaints? In the wake of several controversial police-involved shootings and claims of abuse, law enforcement agencies rushed to adopt the technology as a means of adding transparency to their operations. The Washington DC policy force decided to study the effects by assigning body cams to specific personnel and having a parallel control group operate without them.

The result? No discernible difference, to which police chief Peter Newsham expressed surprise — and some pride:

“We found essentially that we could not detect any statistically significant effect of the body-worn cameras,” says Anita Ravishankar, a researcher with the Metropolitan Police Department and a group in the city government called the Lab @ DC. “I think we’re surprised by the result. I think a lot of people were suggesting that the body-worn cameras would change behavior,” says Chief of Police Peter Newsham. “There was no indication that the cameras changed behavior at all.” Perhaps, he says, that is because his officers “were doing the right thing in the first place.”

Agencies began adopting the technology before any serious study had taken place on its impact. To some extent, public pressure over use-of-force incidents drove those decisions. In other cases, the relatively low cost for recording interactions might have made it seem a good way to cover themselves if allegations of abuse or worse arose. However, before this two-year study took place, no reliable study existed to suggest that the cameras would either lower complaints or improve performance, so the adoption of systems for this purpose was more speculative than fact-based.

This study may wind up being definitive, one researcher tells NPR’s Nell Greenfieldboyce. However, it might require repeated studies under this model to fully grasp its significance, because the Washington DC police force has had long practice at improving performance even without body cams, having spent a decade under federal supervision:

“This is a very methodologically rigorous study. It is very well done. And that’s not a small issue, because there have been many studies of body-worn cameras that are not rigorous,” says Michael White, a researcher at Arizona State University who has studied body-worn camera programs in Tempe, Ariz., and Spokane, Wash. …. “They’re hiring the right people; they’ve got good training; they’ve got good supervision; they’ve got good accountability mechanisms in place,” White says. “When you have a department in that kind of state, I don’t think you’re going to see large reductions in use of force and complaints, because you don’t need to. There is no large number of excessive uses of force that need to be eliminated.”

Thus, when Newsham says that his department was “doing the right thing in the first place,” he’s got a factual basis for that claim.

So should law enforcement agencies invest in these systems at all? Civil-rights activist Harlan Yu tells Greenfieldboyce that they could do more harm than good:

“This is the most important empirical study on the impact of police body-worn cameras to date,” Yu says. “If cameras don’t decrease use of force, don’t decrease the number of misconduct complaints and don’t change officer behavior, then what are we adopting cameras for?”

If they continue to adopt them, it will be for the same two reasons: being seen as taking action, and to have a record of all interactions. The latter makes complete sense for the same reason that call centers almost universally record phone calls. It doesn’t really improve customer service quality unless management makes specific (and intensive) use of it for that purpose. I can’t go into details, but you wouldn’t believe the kind of conversations employees have even when they know they’re being recorded.

The best case for the recordings is to follow up on complaints and determine the facts of the situation. The costs may be considerable, but if it saves a city from just one multi-million-dollar settlement, it’s probably paid for itself. Police officers who operate professionally have the most to gain from the technology for that reason, and will eventually adopt it enthusiastically. In the long long run, that might tend to attract better suited recruits and put more successful officers in place to train them, but in the short run, the potential to unravel controversies has a very significant value outside the parameters of this study.