Drink driving.

My fiancés Dad has always been drink driving. He admits he does it but has never been caught. Now my fiancé does it and thinks he's always fine to drive. Last time he was on a night out he had a shit load and drove back from somewhere 3 towns away from ours. I just spoke to his Dad as they were heading out to the pub and he said yeah we're driving and drinking, I said well you shouldn't that's silly and he just said yeah but it's what I do. I think that's a piss poor example to show your kids and it's obviously rubbed off on my fiancé. It's a selfish thing to do and I can't seem to get through to him.