To what? Please be specific. Change it from innocent until proven guilty to guilty until proven innocent. Or, perhaps model it after Italy, where the prosecutor can appeal a decision and try the individual all over again?
How about - Have an independent body do investigations and prosecutions of Police Misconduct, instead of the Police and DA's themselves. That would be a good place to start.
We could also end the drug war, because that's stupid. End no-knock warrants. End "Middle of the Night Raids".
There's a whole bunch of things we COULD do... you know, like treating blacks with the same respect we treat white people... That would be a thing.