In reply to spartacus:
The "good guy with a gun" is actually on the wrong side of the law. Anyone who believes that the modern law is right would have him in front of a court, tried for murder. Murdering a "bad guy" is still murder and it's not up to him to discriminate good from bad, anyway. He's not a judge and, if he were, he necessarily wouldn't have any executive role.
Circumstance could sway the court to lenience, perhaps, but the point should still be made -- he killed someone and killing is against the law.
Without this, society degenerates into anarchy. There is, in effect, no law because individual "good guys" are tasked with acting in both judicial and executive roles at once. The third part of the trinity of modern governance, legislature, is rendered irrelevant, replaced by popular opinion and on-the-spot consensus on which guy is "good" and which is "bad".
If I, without perfect knowledge of the situation, observed the "good guy" of this story chase and shoot the "bad guy", how should I act? If I see a police officer gunning down a black man before the eyes of the man's family, will shooting the police officer be a heroic deed?
This is not civilisation. This is chaos and, frankly, I'm extraordinarily thankful that I don't have to live it every day. I pity those who do -- particularly those who oppose this status quo.