If you shoot someone, there’s a rule you need to remember, if you have an avenue to retreat from the situation without any harm to yourself you need to take it, the lawyers will emphasize this at trial and will win the argument and you will most likely go to jail and loose everything in the outcome.
...unless you're in a "Stand Your Ground" state. In that case you only have to determine that your life IS in danger and the attacker is breaking a law. You are not required to attempt to run away and see if the attacker keeps attacking you before you defend yourself.
Still, sometimes just because you can, doesn't mean you should.