The body cam revolution: What it has, and hasn’t, accomplished

Body cameras aren’t a perfect solution to the need for police accountability. But they are still an important way to provide the public at least some facts about crucial law enforcement actions.

When former Baltimore cop Peter Moskos returned to his old beat during a ride-along recently, the banter was lighthearted until his partner turned to him and said, “Body camera on.”

The mood in the squad car darkened. “You instantly thought, ‘God, what might I say?’” says Mr. Moskos, now a criminologist at the John Jay College of Criminal...