They (cops) always let them board the aircraft. Contrary to popular belief around here is there is NO law in any state against being drunk at an airport, being drunk in uniform, or coming to work drunk.

The law says you can't operate (or in many places "control" or "possess") a vehicle. More than one allegedly drunk pilot got off the hook, after being confronted at security, by claiming they had to come to airport to use the ops phone to call in sick and then nonrev home, or somesuch. The cops assigned to the airports wised up. TSA is in on it too, even though any smurf worth his salt is drooling and about to piddle himself at the prospect of collaring a drunk pilot, they all know they have to keep a straight face and call the cops after you head to the gate.