The Bush Administration calls prisoners at Guantánamo Bay "the worst of the worst," but one of its own top officials says at least a third never belonged there. The US Supreme Court says they have the right to challenge their detention, but dissenting Justice Scalia warns that could lead to Americans being killed. Out of 770 Guantánamo detainees almost 500 have been released; 60 more have been cleared. Do they pose a danger? We hear about the most extensive investigation so far into who they are and how they got to Guantánamo Bay.