Has the concept of self-defense totally escaped you? Should Zimmerman have let Trayvon continue to beat him, even if it killed him? It may turn out that this was not a self defense case, but certainly bare hands can kill.
Let me explain something: Working the grave-yard shift at a convenience store - a thug called the store from the outside phone booth - stating he had a gun pointed at my head and demanded that I take the money from the register to the door. I pretended to follow his commands - and promptly locked the door.
Lucky for me - I was training a young black guy that night. He managed to ID the perp - hit the alarm button and turn the lights out - SAVING MY LIFE!!!!!
Life experience builds wisdom.
To add, all Zimmerman has to argue is that he was losing consciousness because of the injury to the back of his head, and if he lost consciousness, he would be at the complete mercy of his assailant.
Thus, he had to shoot to save his own life. He only shot to stop the felonious act by Martin. It was a tragic consequence that Martin died of his wound.
His attorney is going to have no problem with this.