Warp said:
...as it seems to me (and the rest of us in this thread, near as I can tell) that a person witnessing what happened would reasonable believe lethal force is justified...
Which still begs the questions of why, how, and whether their explanations would be convincing.
One problem is that with the particular incident referred to by the OP, we know, based on hindsight and information available now which might not have been apparent to a witness at the time, that some thugs were beating up some innocent folks. Sure it looks like someone should have intervened, but that's based on what we know now -- not necessarily on how things might have appeared to someone who had just come upon the incident as it was unfolding.
So tomorrow you turn a corner and see one man knock another man to the ground. On what bases would you decide that (1) the guy on his feet is the thug beating up an innocent man; or (2) the guy on his feet is defending himself against a thug?
Warp said:
...where the law simply says the person must reasonable believe,...
And you're basing that on your interpretation, in a vacuum, of a few words in a statute. But until you find a Georgia court of appeal decision applying those words in a defense-of-another case, your interpretation doesn't mean much.
In the defense-of-another cases I cited, the court of appeal didn't consider reasonable belief. Understanding how these things work, that leads me to conclude that the defendant didn't even raise a question of his reasonable belief.
And in any case, your mistake in a defense-of-another incident necessarily means that you hurt or kill an innocent person in order to help someone who doesn't deserve your help.
Whenever this topic comes up, a bunch of the participants seem to assume that they will magically know who the good guy is and who the bad guy. But how will you know?
Warp said:
...as judged by peers if necessary...
What makes you think you'll be judged by peers?
Nothing in the law of the United States entitles you to a jury of your peers, i. e., people belonging to the same societal group, especially based on age or status, as you. You are entitled to an impartial jury (Sixth Amendment to the Constitution of the United States).
(The notion of a "jury of one's peers" comes from Magna Carta and was indeed intended to refer to being judged by one's equals. Magna Carta was forced on King John by the feudal barons to protect their interests. Their first concern was that they be judged only by nobles of similar rank. And indeed until relatively recently, a British noble charged with a crime was entitled to be tried in the House of Lords. The last trial in the House of Lords was in 1935, and the trial jurisdiction of the House of Lords was abolished in 1948.)