The first of these is the utter incompetence of the battlefield vetting in Afghanistan during the early stages of the U.S. operations there....The second dimension that is largely unreported is that several in the U.S. leadership became aware of this lack of proper vetting very early on and, thus, of the reality that many of the detainees were innocent of any substantial wrongdoing, had little intelligence value, and should be immediately released.
....The fourth unknown is the ad hoc intelligence philosophy that was developed to justify keeping many of these people, called the mosaic philosophy. Simply stated, this philosophy held that it did not matter if a detainee were innocent....All that was necessary was to extract everything possible from him and others like him, assemble it all in a computer program, and then look for cross-connections and serendipitous incidentals.
....Thus, as many people as possible had to be kept in detention for as long as possible to allow this philosophy of intelligence gathering to work. The detainees' innocence was inconsequential. After all, they were ignorant peasants for the most part and mostly Muslim to boot.
Read the whole thing. He presents some compelling evidence that although shutting down Guantanamo might be politically difficult thanks to Dick Cheney's "recent strident and almost unparalleled remarks about the dangers of pampering terrorists," it's almost certainly not much of an operational challenge at all.