the problem with the law is that the fight happened after zimmerman had run 2 blocks from his truck to the spot of the dead body.
He told the 911 operator that the 'asshole' and 'punk' was running away, was going to get away.
He was pissed off, he had a gun, and he chased a kid 2 blocks. Then they fought, he wasn't doing so hot, so he shot the kid.
He created a fight with an unarmed person who broke no law.
And I think ANY of us - if an armed man, 10 years older, has chased us 2 blocks in the darkness - we're hitting him with a fist, a rake, a brick, or ANYTHING ELSE when he finally catches us. Only an idiot would greet the armed chaser with "How can I help you, sir?" The minor felt scared as shit, and fought. As would any of us.