There are internal units in police departments that review all cases of fatalities and any incidents involving inappropriate use of force by a policeman. I think this is where you could have real reforms that make a difference.
If it is a three-panel review committee, have two of the three people doing the review as ordinary citizens, not policemen. This would ensure there is no conflict of interest and the judgments were rational and fair, as opposed to the current system where the internal units with nothing but police personnel have in inbred tendency for the police to protect themselves — an obvious conflict of interest. Having two out of three members of that review committee being non-police would eliminate this obvious conflict of interest.
Also, the findings and final judgments of these internal committees have to be made public so there is transparency in their proceedings and adjudications. Right now, much of this is considered protected information and shielded from the public. That has to change. Otherwise, the public will continue to have no faith in these secretive internal reviews so subject to obvious conflict of interest.