Interesting thing to note, in reference to the Trayvon case: this father didn’t mean to kill the guy. He just beat him with his hands, and the guy died. No gun involved.
Even if a person doesn’t MEAN to kill you, if they start beating your head you are in danger for your life.
The eyewitness testimony that Trayvon was banging Zimmerman’s head on the concrete, coupled with the injuries to Zimmerman’s head, are all the evidence necessary to decide that Zimmerman is innocent. Doesn’t matter who started it; at that point Zimmerman’s life was in danger and lethal force was justifiable.