Waiting for the first city to wake up and order police to carry video cameras instead of guns. That way, they can record what happens on the call for social workers, judges and social media mobs to based their judgements on.
Let the crimes happen, and document it. That way, the Cops can't be accused of anything -- other than refusing to get in the middle of the situation.
If the public complains, tell them, "We decided that if two people are fighting, and one of them dies, it's no different numerically than police intervening and shooting the assailant. If two are engaged in a knife fight, nobody is innocent. We'll let the law of the jungle decide who lives or dies. We can later decide from the recorded evidence who is at fault -- the same evidentiary standard Cops are being convicted with today."