I don't want to excuse the abuses but I think in a sense the cops are the victims of bad politics and management. Obviously shooting innocent people is not acceptable but on the other hand they are being thrown into a bad situation and don't get much help coping with that. I know a guy (very nice guy) who started as a cop two years ago. Since then he had to shoot somebody in the leg who attacked him with a knife, had to deal with a teenage girl hanging herself, lots of domestic violence and a lot of other really bad stuff that's very tough to deal with. They don't get any psychological counseling so a lot of the old-timers are either alcoholics or have some other kind of psychological damage.
In the end politics needs to have the courage to address the underfunding and also address the training and management situation. They don't want to do either because it may cost money so the bad situation just keeps going. Reminds me of the healthcare situation where even the most blatant problems go unaddressed because it's more important to do partisan fighting instead of addressing issues. I think it's well understood that the drug laws are damaging so it would be a good start to clean them up.