A Mauritanian national, Slahi was accused in the 9/11 Commission report of helping to recruit members of the German al Qaeda cell that took part in the attacks, according to the Wall Street Journal.
Conservative media -- beginning with the Weekly Standard and Fox News -- have pounced on the case. Slahi currently holds the feature spot on the Web site of Keep America Safe, Liz Cheney's group ("Free Mohamedou Slahi? Meet Him First").
The judge's order, granting Slahi's petition of habeas corpus, is still classified. But, according to a 2007 story in the Wall Street Journal, the military prosecutor originally assigned to the case refused to go through with the prosecution after he found "evidence the prisoner had been beaten and exposed to psychological torture, including death threats and intimations that his mother would be raped in custody unless he cooperated."
Slahi's attorney told the Journal: "They were considering giving him the death penalty. Now they don't even have enough evidence to pass the test for habeas."
It's not clear yet whether Slahi will actually be released, and an appeal by the Justice Department is possible. "We're reviewing the ruling and considering options," says Dean Boyd, spokesman for the DOJ's National Security Division.
The case has now been picked up by a Republican Senator -- Kit Bond of Missouri -- who in a statement yesterday tied the Slahi order to the Obama Administration.
"While Holder's Justice Department should appeal this outrageous decision, I'm not holding my breath," Bond said. "Holder seems more intent on closing Guantanamo Bay than keeping terrorists locked up where they belong."