Since the '70s it feels like law enforcement (and juries to some extent) are informed by two movies much more than the Constitution and case law: Dirty Harry and Death Wish.
I saw a interesting clip on TV a while back where they played several clips of various popular police dramas in which the main characters use wildly illegal or unconstitutional tricks to get confessions from criminals. Things like physically assaulting them while contained and. turning off cameras in interrogation rooms to do so. The point it was trying to make was that this "desensitized" people to police violence. Of course, the criminals in the clips were things like child predators, serial killers, etc. so it was all justified.