When you're written up by campus police, because they probably wont involve the actual police. He will have to pay a fine probably around $100, meet with one of the deans, do that stupid online drug/alcohol class that takes 5 hours, and he will be put on probation. For your first offense you usually get a warning, but he likely will be put right on probation. He can always appeal if you want. The dean will read him his rights and will explain the process, it does depend on what his friends say though, because they will call everyone in to give their side of the story. Im speaking from experience. Just dont lie, or at least dont get caught in one, so make sure you know what the rest of the friends were doing. Also, since it was with his fraternity bros, cant you get the actual fraternity involved (and their lawyers)
**** maybe if he has an injury, you can sell it that he uses it for its medicinal purposes and blow a lot of smoke up their ***, because they will ask why you were smoking/drinking. Might have to write a formal apology also.