Independent inquiries should take place every time a cop draws a weapon. That includes batons, Tasers, firearms, blackjacks, saps, and anything else that can kill. A full-scale investigation should happen if a cop fires a weapon even if death or wounding does not result.

Such methods protect both the citizenry AND the cops.

But of course, most places in the US have citizen review boards...and not all of them rubber-stamp police actions.