I read somewhere about an idea that would create a registry of bad cops. I guess it would work something like the assorted child abuse registries with the intention that a cop who got fired from one area for bad behavior couldn't just move to the next state and start work as a cop again.
I can't help thinking that where major crime, especially violent crime, is concerned we need the police to be able to respond quickly and with enough force to stop the criminals. At the same time for lower level stuff we need a less militarized response and to make sure police are trained in de-escalation techniques.
It seems there's a balance to be struck between holding the police properly accountable for their behaviors and recognising that they work under stressful situations where split-second decisions are often required. When a cop doesn't have the luxury of time it's easy to see why they might shoot a man holding a table leg when responding to a report of a man with a gun (something similar happened in the UK some years ago). At the same time once a suspect is restrained perhaps any further use of force should be assumed to be unreasonable unless it can be justified.
I suspect that police unions may resist the removal of overly aggressive cops, although resisting something that clearly furthers the overall purpose of policing (i.e. making the public safer) would seem to play right into the hands of those who would rather just do away with the police department.