You lost me at "What if the rioters are legitimately trying to prevent a fascist regime from taking over?". I bet many at the Capitol believed they are "legitimately trying to prevent a communist regime from taking over"... what you are basically saying is "violence is ok as long as I personally believe it's ok".

I'd say require the police line to wear body cams, have them on, and then require connecting a shot to a specific act. That would also serve as good Pavlovian training for people who think violence is ok as long as they personally think it's ok. The definition of what act can vary, but what I meant above is limited to this instant, targeted reaction - what I want to see is a specific "protester" throw a rock at police, or force entry, or set something on fire, and instantly gets shot; with camera evidence of both. Of course, I'd also accept arresting (and prosecuting with real punishment, not releasing after a few hours), but I don't believe it matters which one is used in the case of violent riots.