you are aware of school's zero tolerance policy, no? and you are aware that he too will face legal repercussions? my friend fought in self-defense cuz he got ganged up by 3 coworkers at after-work party... as the result, he lost his job and faced a jail possibility as he got arrested and charged with aggravated assault. I got him an excellent lawyer and in the end.. all he got was a probation.
again... is that person's life in danger? no. then just walk away and take a high road. sometimes life's not fair. there are far far far too many people who ended up just like him.
