It only works where decent people have been disarmed by unconstitutional laws.
Really? Because Missouri is a "shall issue" state. The fact is for a all the "I'd kill 'em all" bravado one sees in these threads, if you pull a pistol and shoot an unarmed person before they hit you, you're pretty much screwed as far as the legal system goes. It may be wrong it's that way, but then again we can't allow every potential fist fight be ended pre-emptively by gunshot either.
And you might not get a chance after they hit you. So best to be aware of your surroundings and avoid areas where this is most likely to happen.