The grant of Mohamedou Ould Slahi’s habeas corpus petition briefly turned years of detention without a criminal charge into a judicial order for release, but the government’s appeal and the appellate court’s remand kept the case open. The proceedings tested not only the evidence offered to justify detention, but also the legal standard for deciding whether a Guantánamo prisoner could be held as part of al-Qaeda. The order was a significant victory, not a final release: after the case returned to the district court, it remained pending.

From petition to district-court hearing

On March 3, 2005, Mohamedou Ould Slahi handwrote a petition for a writ of habeas corpus, asking a federal court to review the basis for his detention. The petition was part of a longer effort to bring his confinement within the reach of judicial review. In 2008, the Supreme Court ruled in Boumediene v. Bush that detainees at Guantánamo had a right to challenge their detention through habeas corpus. That decision provided the legal setting in which Mohamedou Ould Slahi’s case could be heard.

Judge James Robertson heard the petition between August and December 2009 in the U.S. District Court for the District of Columbia. The central question was whether the government had established that Mohamedou Ould Slahi was part of al-Qaeda at the time relevant to his detention. The litigation therefore required the court to consider both his earlier association with the organization and the government’s account of later contacts, rather than treating an allegation of past involvement as automatically decisive.

Evidence and the question of membership

The government’s case did not rest on an allegation that Mohamedou Ould Slahi had fought against the United States or taken part in the September 11 attacks. In its later description of the case, the U.S. Court of Appeals for the D.C. Circuit said the government relied on an oath of allegiance, associations with al-Qaeda members, and assistance that included hosting leaders and referring aspiring jihadists to an operative. The dispute thus concerned the meaning and significance of relationships and acts, and whether they established continued membership when he was detained.

Mohamedou Ould Slahi had joined al-Qaeda in 1991 and sworn allegiance then, but maintained that his participation ended with the fall of the communist government in Afghanistan. The district-court record described his later interactions with people who remained active in al-Qaeda as sporadic. Judge Robertson considered whether those contacts demonstrated continuing membership, while also recognizing that they could be consistent with an effort to keep some distance from the organization without making himself an enemy of its members. The legal issue was not simply whether contacts existed, but what they could reliably prove about his status at the time of detention.

The reliability of information gathered in custody formed an important backdrop. Mohamedou Ould Slahi had been subjected in 2003–2004 to a special interrogation plan approved by Defense Secretary Donald Rumsfeld. Investigative files included detailed memoranda about interrogation sessions and how information was obtained; although the files remained classified, accounts of them appeared in government reviews and a Senate Armed Services Committee inquiry. One documented tactic was a fictitious letter concerning his mother. These records mattered to the broader question of how statements and intelligence should be assessed, especially when accounts produced under coercive conditions could be mistaken for independent evidence.

The prosecution history also underscored the limits of what the government had established. No charge sheet had been drawn up against Mohamedou Ould Slahi in Guantánamo, and no defense attorney had been appointed to represent him before a military commission. Stuart Couch, a military prosecutor who withdrew from the case after reviewing evidence of torture, later said that the intelligence reports did not implicate Mohamedou Ould Slahi in an overt act in the conspiracy to attack the United States. At the habeas hearing, the government did not argue that he was a major al-Qaeda figure or that he had participated in an al-Qaeda attack or plan. Those points did not themselves resolve the detention question, but they distinguished the government’s case for continued detention from a criminal prosecution for involvement in the attacks.

Release order and government appeal

On March 22, 2010, Judge Robertson granted the habeas petition and ordered Mohamedou Ould Slahi’s release. The decision came amid a broader series of Guantánamo habeas cases: by April 1, 2010, the government had lost thirty-four of the forty-six cases decided. The order represented a judicial finding that the government had not justified this detention under the standard applied by the district court; it did not amount to a criminal acquittal, since no criminal charge had been brought.

Four days after the ruling, on March 26, the Obama administration filed a notice of appeal. The appeal placed the district court’s legal approach under review at a time when the appellate court had accepted a looser standard in other cases for deciding whether a detainee was part of al-Qaeda. Under the earlier approach, the district court examined whether the government showed active membership at the time of detention. The emerging appellate standard did not require the same showing that a prisoner had been carrying out al-Qaeda orders or directions when taken into custody.

Remand and unresolved outcome

On November 5, 2010, the U.S. Court of Appeals for the D.C. Circuit sent the case back to the district court for rehearing. The appellate court carefully distinguished detention from criminal liability: it noted that the government had not criminally indicted Mohamedou Ould Slahi for material support to terrorism and was not seeking detention on the ground that he aided the September 11 attacks or purposefully and materially supported forces engaged in hostilities against the United States and its partners. Instead, the government was expected to rely again on the argument that his contacts with active al-Qaeda members in the 1990s showed he remained part of the organization.

The remand changed the framework in which those connections would be assessed. Under the appellate court’s formulation, even connections that did not independently prove membership could make it more likely that Mohamedou Ould Slahi belonged to the organization when captured, and could therefore remain relevant to detention. The court did not itself determine that the government’s allegations were true; it returned the case for another hearing under the revised standard. The distinction between evidence that establishes an act, evidence that suggests an association, and the legal inference drawn from that association remained central.

The practical consequence was that the release order did not end Mohamedou Ould Slahi’s confinement. The case was still pending after remand, and he remained at Guantánamo. The proceeding therefore ended, for the time being, not with release or a criminal trial, but with a new round of judicial review. Its unresolved status exposed the distance between a court’s finding that detention had not been justified under one standard and the government’s continued effort to defend detention under another.