Why was I detained by police at Dulles Airport?

It appears that even the FBI isn’t sure what, if any, legal basis local law enforcement officers have for detentions of passengers at airports, such as I experienced in May at Dulles Airport, even when (as I don’t think was the case with me) the would-be traveller is supected of matching a listing on the “selectee” or “no-fly” list.

According to e-mail messages which the FBI had fought hard to keep secret, but which were released in response to a court order in a lawsuit under the Freedom of Information Act on which I have reported previously:

I believe that “investigative detention” is the basis for the local LEO [law enforcement officer] holding individuals until the FBI shows up…. After you [i.e. FBI agents] arrive, however, if there is nothing in NCIC, such as an immigration violation or an arrest warrant and they want to leave, they can leave, unless you find something for which to arrest them…. (A lot of LEO’s don’t like using that surrogate authority, which is why we [i.e. the FBI] have had all these deputation issues over the last couple years….)

TSA and local LEO are inquiring as to the PC [probable cause] for detaining individuals that have been identified on the No Fly or Selectee list with more than the name match. They are concerned about the legality of the detention. They need to know the PC for which they are detaining the individuals until the FBI shows up to interview the individual.

There’s no indication in any of the expurgated documents released in the case that the FBI came up with any probable cause to give local police for detaining people at airports, in the absence of warrents for their arrest.

So what was the probable cause for my detention?

[Follow-up, 28 July 2006: TSA report on what happened to me at Dulles Airport ]

[Follow-up, 28 September 2006: Kip Hawley is an idiot. ]

[Follow-up, 27 October 2006: TSA says their press releases are secret ]