Over the past few years, the idea of requiring that police officers make use of so-called “body cams” has gained currency. Note that this is quite different from simply allowing civilians to record on-duty police officers, a right that shouldn’t even be in dispute. Instead of waiting for a world in which every civilian records every encounter with the police, at least some students of law enforcement have argued that police forces themselves should move in this direction. Last fall, Guardian correspondent Rory Carroll reported on the small southern California city of Rialto, where the local police department has affixed small body cams to all of its officers. The results were dramatic. Carroll cites a jaw-dropping study, which found that in the year following the introduction of the body cams in February 2012, public complaints fell by 88 percent while officers’ use of force fell by 60 percent.

The success of the Rialto experiment makes intuitive sense. When we know that we are being observed, it affects our behavior in all kinds of ways. We become more aware of how others might judge our behavior, so we feel a not-so-subtle pressure to act in socially acceptable, rule-following ways. Moreover, the existence of a video recording allows police officers to revisit exactly how they performed in high-pressure situations. Our capacity to remember past events is notoriously faulty. There is a universal human tendency to fixate on some things while neglecting others. Video recordings can help correct for these deficiencies. In instances where something does go wrong—due to malice on the part of the police, a civilian, or something else entirely—the video provides a record that can help investigators sort out how things really came unstuck. In politically sensitive cases, in which all sides fear getting railroaded, a black box of this kind would be a godsend.

If police officers wore video recording devices, there is at least some reason to believe that Michael Brown would still be alive.