Jeff and I had this discussion a few weeks ago.

- - Posse Comitatus in action - - Not long ago, I happened across an odd site. I was crossing the Hudson river on a ferryboat and I noticed a rather mean nasty looking gray navy patrol boat sitting in the harbor. Nothing unusual given the extent and height of alerts since 9/11, but if you looked close, the U.S.S. Tornado was flying a Coast Guard ensign. The boat must have come off a drug interdiction patrol. Precisely BECAUSE of the PCA, the NAVY cannot stop a civilian boat. However, the Coast Guard in its law enforcement role has the ability to stop any vessel within our limits and any American vessel on the high seas.That is why you see a Coast Guard boarding party on a navy ship. when they need to stop someone they just run the coast guard ensign up the halyards and turn the boarding party over to the CG. Very resourceful and legal.
BillD.