if you're gonna draw / pull your firearm, you always shoot to kill. that's why it has to be an actual life or death situation, not just fear or preemptive. my carry firearms have the most lethal rounds available to civilians, not target rounds. If I have to draw and fire, I will not be trying to wound you.
many times someone draws and fires without cause. I recall the armed robber in a small restaurant, he robbed patrons at gunpoint but never fired. As he was leaving, a patron drew his firearm and fired at the robber hitting him in the back. That was unjustified IMO. Now, had the robber fired his weapon or shot someone, that would be justified.
If you shoot someone in the back, that means they're fleeing and not an imminent threat to you; now if they shot someone else before fleeing, then you might have justifiable cause.
the last thing I want to do is take someone's life and I hope I'm never in that situation; but if I am, I am prepared to do what's necessary to protect my family and myself; the rest of the public can protect themselves "they're not my concern; unless they are children".
just sayin'