Ah, ah, ah!And which one of them was in the right, merely defending themselves with deadly force, and which one was the original attacker?
Read the hypo:
This is all we know. Maybe there was provocation; maybe the attacker thought he was justified, but to any casual observer, this is an obvious violent crime. Furthermore, the perpetrator's subsequent action (attempted flight) is consistent with his having committed a crime. (In a subsequent criminal action, the prosecution could introduce this as evidence of his knowledge of guilt.)You're walking around somewhere, late at night. You see one person attack another with a knife. He fights back and loses. The attacker is obviously hurt, looks around, sees you and begins hobbling away.
Indubitably, and I hope I've made clear that I am far from certain on the legal answer to the question. Also, everything I've ever heard from law enforcement personnel is that they don't want civilians trying to do law enforcement's job: you look out for the victim; we will deal with the perpetrator. I'm quite content to follow that request.Edit: I'm not trying to be a smartass (well, no more than usual) - but when you walk around with deadly force in your belt, you gain a little perspective on employing it, and realize that appearances can be very deceiving.
EDIT: cross-posted with Erik.