Keoni is on point as usual. If you ever press the trigger in self-defense, it'll be because you felt you were manifestly justified in doing so. The thing to remember is that regardless of how righteous it may have been, someone has a bullet in them, and they're either on the way to the hospital or a slab because of actions you took. Self defense is an affirmative defense, which means you're saying, "Yessir, I committed the crime of killing that fellow. Here's why I shouldn't be punished for it." Even in a state with strong self defense laws, they still frown on citizens shooting each other, so keeping a tight grip on what comes out of your yap is critical.