If I were him, I'd try to find out if there is anything outstanding on him. I've known some very good friends for years who never told me that "back when I was blah blah blah... got arrested for blah blah..." and the final straw... "NOTHING EVER CAME OF IT."
Some random ticket you thought you'd taken care of that and now there's a warrant out you don't even know about? I suppose he could walk into the nearest police office and ask them to run his name? Somebody should probably go with him or maybe contact a lawyer beforehand to cover all his bases. Yup, I'm talking out my butt here, but you never know.