I didn't go for that because "protect" is too vague. Anybody would "protect"; the question I thought is "at what point would you kill". "Protect" doesn't mean "kill".
Would you kill the criminal if nessessary to "protect" yourself, your family or a another person perhaps a stranger?
As I already said in my first post, only if it were directly and immediately life-threatening. Meaning, at the point where there was no other alternative at the risk of one's own death. Again, "protect" doesn't necessarily mean "kill". It rarely does. "Disable" accomplishes the same purpose without taking a life.
Some of these answers here, such as "I would kill any criminal who was armed in the commission of a crime" are just off-the-wall vigilantism and IMO way over the line. If we were individually qualified to act as judge, jury and executioner on a moment's notice, there would be no point in having a system to prosecute criminals. We could just be sovereign savages and walk around wasting anyone we want. One would hope we had progressed beyond that stage. There's a point where given the option to "disable" or "kill", some of us want to go with pure vengeance and ourselves become the killer.
I keep seeing that scene in the movie "Witness" where the little boy comes across the cop's gun, picks it up and inspects it -- the old man asks him, "would you use that gun to shoot a man?" and the kid says "I would only shoot the
bad man". The old man then asks, "you can see inside that man's
heart??"
That wisdom seems elusive these days. At least on the internets.