This is difficult when police literally have a union. If the union were acting in good faith they would be eager to learn & fire. Instead we get the “blue wall of silence” & turn otherwise “good” cops into ones indistinguishable from “bad” cops.
I mean there’s even a “good cop/bad cop” trope that’s got to be the best example of this kind of behavior—I can’t count how many times police are complicit with straight up torture and abuse of rights on Law & Order.