Video from police body cameras gives us a window into their world, as they rush into danger. They can also be used to hold officers accountable for their actions. Many hoped those devices would make it easier to do just that, especially in the cases of police brutality.

Here in D.C, a study says body cameras don't impact officers' actions. The study looked at 2,200 officers for more than two years. Those who had the cameras on and those who didn't, had no difference in behavior, according to the study.

RELATED: Study: body cameras have no effect on use of police force

The study, facilitated by The Lab @DC, used science to measure the impact of body-worn cameras in the District. The data was collected from June 2015 to March 2017.

“Our police department has always valued a strong relationship with the residents and visitors it serves. We invested in one of the most comprehensive deployments of body-worn cameras in the nation to ensure even greater transparency and accountability,” said Mayor Bowser. “As we conclude this comprehensive study, we will recommit ourselves to always evaluating what works—and what does not—to better serve our residents and create a safer, stronger DC.”

Some civil rights researchers believe the study shows that it's time for some departments to reevaluate the use of those cameras.

"This study shows that maybe these body-worn cameras aren't doing the job we thought they might be able to. If we can't measure any tangible benefits of body worn cameras, maybe the city or police department should think about other ways to invest millions of tax-payer dollars," said Harlan Yu, a researcher with Upturn in the district.

While the results may not necessarily be tangible, the department's chief says the cameras are a major asset to the officers.

“Our comprehensive body-worn camera program is one of the ways we can continue building on the trust we have with the community,” said MPD Chief Peter Newsham. “Not only does it offer greater transparency, it has allowed us to evaluate split-second decisions officers are making to improve our training. The comprehensive study only reassures us that body-worn cameras are an invaluable technology for our department and the community.”