Seven years ago, the Pentagon began imprisoning men it described as "very hard cases," "the worst of the worst" among terrorists in American custody, at the U.S. Naval Base in Guantanamo Bay, Cuba. Since then it has released more than 500 of them. "What's left," Vice President Dick Cheney declared last week, "is the hard core." That was right before the Pentagon released half a dozen more.

Unless the Bush administration recklessly loosed hundreds of hardened terrorists on the world, the president's men evidently were mistaken when they said every detainee belonged in that category. That pattern of error reinforces the argument against allowing the executive branch to wield the kind of unchallengeable authority it asserted at Guantanamo.

As President Obama proceeds with his plan to close the prison, he should recognize that Guantanamo is not so much a place as a state of mind. It's an attitude that says: We know who the bad guys are, and we're not about to let anyone endanger national security by second-guessing us.

The Bush administration manifestly did not know who the bad guys were. Its methods for identifying "unlawful enemy combatants," defined as anyone, anywhere who belonged to or supported the Taliban or Al Qaeda, were sloppy and haphazard.

More than 90 percent of the 779 men held at Guantanamo were captured not by Americans but by Afghan militiamen, Pakistani forces or other parties of dubious reliability, often in anticipation of bounties the United States had promised. Many detainees were either minor hangers-on or entirely innocent, held based on the uncorroborated word of self-interested captors or of prisoners eager to please interrogators who used "enhanced" techniques to extract accusations. Continued...