In my opinion, the one step which would really lead to accountability and change in law enforcement:
Have the supervisory and command staff and the responsible elected officials face the lawsuits and suspensions and investigations and dismissals and jail time — instead of the individual officers they are responsible to select, train, supervise, and discipline becoming the scapegoats to conveniently throw under the bus and be chased around by an outraged and pitchfork wielding public. Those leaders encourage the public and the media to buy their premise that with rank comes immunity — not responsibility.
When there is a bad act or outcome in public safety, it is occasionally the work of a deep cover evil being who has infiltrated a healthy organization. But mostly, it is the predictable result of a flawed agency or unit culture which tolerates or promotes evil (or just incompetence) by selecting the wrong individuals to receive the wrong training to do the wrong things with inadequate supervision.
Address the cause, not the outcome.