Burn qualified immunity to the ground and salt the earth. This would be the simplest way to keep police accountable for their behavior. It would also imply a massive change in how policing is done (demilitarization), so that's two big wins.

We can lay a lot of the rotten police problem in the USA, and the world, at the fact that the accountability just isn't there.

I always thought only hiring police officers from the area being policed was a good start.

I don't mean that if you hire someone they have to move into the district. I mean that your pool of hires is the people who have already lived in the district for a particular amount of time (years).

The locals know what laws not to enforce and how to gain the trust of the community.