You can't grass the bloke up. That's the sort of thing a dirty Jack would do.

Someone mentioned the potential for him to conk out when driving to mow down innocents on the street. Nearly every person in a boozer of a night has had more than two pints of grog. What are you to do, whisper down the dog and bone every two minutes to the old bill that a punter who has just left is over the limit and potentially could get behind the wheel? Remember, snitches get stitches.