NEW YORK — What if Michael Brown’s last moments had been recorded?

The fatal police shooting of the unarmed black 18-year-old in Ferguson, Missouri, is prompting calls for more officers to wear so-called body cameras, simple, lapel-mounted gadgets that capture video footage of law enforcement’s interactions with the public. Proponents say the devices add a new level of accountability to police work.

“This is a technology that has a very real potential to serve as a check and balance on police power,” says Jay Stanley, senior policy analyst at the American Civil Liberties Union.

The case supporters make is simple: Cops and criminal suspects alike are less likely to misbehave if they know they’re being recorded. And there’s some evidence supporting it. In a recent Cambridge University study, the police department in Rialto, California — a city of about 100,000— saw an 89 percent decline in the number of complaints against officers in a yearlong trial using the cameras.

The number of times the police used force against suspects also declined. After the trial, the cameras became mandatory for the department’s roughly 100 officers.