How do you tell when a terror watch list is bloated beyond all meaningfulness?

The black-and-white mug shot shows a young man with tousled hair and a wispy beard, staring into the camera with steely eyes.

It was 1977 and Miguel Rodriguez had just busted a pane of glass in the Statue of Liberty's crown and hung out a Puerto Rican flag during a nine-hour siege staged by associates of the FALN terrorist group.

Like the others, he was arrested. At that moment, only a handful of NYPD officials knew Rodriguez was really an undercover cop who had penetrated the group.

Fast-forward more than three decades since his heroic and dangerous assignment and Rodriguez is facing a new threat: U.S. Homeland Security thinks he's a terrorist.

Rodriguez, who retired from the NYPD as a sergeant in 1994, has been detained twice in the past month at area airports because of his old arrest and conviction.