I would say...old enough to do what he did, so let him sort himself out. Or leave it up to GF to decide...either way, detaching might be the best thing on your part. My oldest brother got busted for a similar thing when he was that age; he didn't go to jail for a "first offense", but my parents left him to sort it out. My thought...if you bail him out, will he learn that he can just continue to do these things because he knows you both will step in and take care of his problems for him?