Zimmerman had the legal right to carry and use the gun. Martin DID NOT have the right to attack Zimmerman.
Why is this so difficult for you or anyone to understand?
You don't know that Martin attacked Zimmerman
It's just a likely (or in my opinion much more likely) that Zimmerman confronted Martin and attacked him or tried to detain him
Rachel Jeantel testified under oath as follows:
Jeantel said Martin told her the man watching him was a "creepy-ass cracker." She recalled suggesting that the man might be a rapist. She went on to say that Martin told her he was going to try to elude the man, and that the teen left the area but that he was still being followed. Jeantel said she told him to run, but Martin replied that he was close to his father's fiance's house. Shortly after, Martin told Jeantel he would run home and then the phone went dead.
Later in her testimony, Jeantel said that when she called Martin back, he told her "the guy is behind me." Jeantel said she heard a bump and then the sound of "wet grass." She said she heard Martin say "get off," the call was cut off and she never spoke to Martin again.