There are good cops who get overpowered by the bad cops and their work ruined. One good cop who earnestly tries to do his or her job can't turn around the perception of their local community. Speaking out is something they just don't do and if you think about it, a person who works 12 hour shifts and actually does their job only wants to go home at the end. That and obviously it is severely "discouraged" by the higher-ups as no one wants to "deal" with "dissent".

The internal hierarchical police system needs to change; the promotion process, transparency, reporting, etc all need to be updated. Training is horrid, gossip is rampant, etc etc. The things I hear from my buddy who until recently was a cop in a major US city are cringeworthy. I'd be surprised if anyone wants to join the police force in the future because even if they don't intend to commit any immoral acts (we can discuss the morality of enforcing laws of course, particularly laws that are based on governmental incompetence or judicial corruption), their good deeds will quickly become overshadowed and they will become disillusioned.