Bars, Clubs and Nightlife Forum

He may have done it and barely remembers it.
That is NOT excusing the action - but before launching into a big campaign against him - if you're comfortable/feel safe about it - TALK to him.
Tell him how upset you are and make him understand that it isn't okay to do that kind of shit.
If he reacts w/ hostility and/or denial - that probably means he knows full well what he did, isn't sorry, and is pissed he got called out.
If he did it w/out thinking it through and was drunk - he'll probably be mortified, apologetic, and have learned to be vigilant of his actions.

Since she hasn't talked to him, we don't know if he's done anything like this before.
It's entirely possible that, if he doesn't remember it, it isn't something he does regularly and he might be horrified by it, and could learn that no, he doesn't get to drink anymore.