What do we want police body cams to do?

Not even the Memphis police chief could dismiss the video footage of 29-year-old Tyre Nichols being fatally beaten by cops in early January. On the day before its public release, police chief Cerelyn Davis declared the attack “heinous, reckless and inhumane.”

Friday night, the rest of the country saw what she meant. Officials released four videos — three from officers’ body cameras and one from SkyCop surveillance footage — that showed Memphis police punching, kicking, and clubbing Nichols, who did not fight back. The videos showed Nichols crying out for his mom, captured a police officer...