I think there are 13 states now where you can defend yourself with deadly force, without the need (or requirement) to flee first. I think they call them "Stand Your Ground" laws. Even if you could walk away, or drive away, and avoid a confrontation, you no longer have to -- just blow your assailant away, no problem, not a crime. There's some cab driver who shot a dude who tried to get back into his cab, and that cab driver is very likely to go free. You lean into someone's car these days, you're taking a big chance of taking one to the brain, and even zombies don't get up from that.