It’s worth reiterating that police are effectively above the law, criminally and civilly. Aside from the obvious conflicts of interest between police and prosecutors, there is a court invented[0] principle that says that cops are immune to even civil suits if they violate your rights. This can only be breached if the courts had previous ruled that their specific actions[1] violated your rights. Since cops can’t go to trial for new abuses, new precedent isn’t being made and cops are for all intents and purposes immune.

0 - Funny how the anti-“activist judges” crowd is silent about the Supreme Court making this doctrine up out of whole cloth.

1 - Down to the terrain in which the abuse happened.