Breaking news says Trayvon punched Zimmerman

[TheWraith]

33. Both, sort of.

To use lethal force, the law requires that you have a reasonable belief that it's necessary to prevent imminent death or severe bodily harm to yourself or another. ("Severe bodily harm" meaning here, for example, beating or rape.) The key phrase there is REASONABLE, i.e. that another person in the same situation would have felt the same. Someone coming at you with a knife or telling you they're going to kill you = reasonable. Seeing somebody with something in their pocket looking at you funny = not reasonable.

Put another way, it IS judged somewhat on what the person thought at the time, so it could be legitimately considered self defense if you shoot someone who claims to have a bomb strapped to their chest, only to find out later that they were a psych case with molding clay. However, that's still calibrated against what the average person would believe. That's part of the reason so many self defense shootings end up going to trial anyway, so a jury can judge what they consider to be reasonable or not.