Most countries actually have some law stating you can't defend yourself to full capability, or something along those lines, the US (and Alaska) are no exception to such laws.
In the US you get one hit for every hit they land on you as a means of self-defense, but even then, if you hit too hard you get sued for "using unreasonable force in self defense".
Here in texas we have castle doctrine and it now applies to cars as well
That means I don't have to retreat from a robber armed or not I can defend my property with lethal force
Same goes for third parties, if I see a robber/rapist/ murderer doing his evil deed I am also allowed to intervene with my concealed firearm(licensed)
In addition even before those laws were passed texans had more self defense rights because anti cattle stealing laws allow you to shoot robbers at night who are stealing your property
Now of course everything has a lawyers spin so I would never advocate gunning down fleeing criminals but if someone is actively committing robbery/rape or attempted murder you're allowed to stop them with deadly force