1. Qualified immunity needs to go, it isn't even law; it was concocted by SCOTUS out of nothing in 1967.
2. A special force that only investigates law enforcement officers and their wrongdoing (like GIBS in Czechia [0]) could help. Not even police can police themselves.
3. A lot more professional education for officers would be good, US officers have less training than their counterparts in other developed countries. [1]
[0] https://en.wikipedia.org/wiki/General_Inspection_of_Security...