The full D.C. Circuit has reversed part of a 2020 panel ruling that a Guantánamo Bay military prisoner, who is being detained indefinitely for supporting al-Qaida, lacks any constitutional due process rights, and ordered a lower court to revisit his substantive due process challenge to his ongoing imprisonment.

In a short order Tuesday, the en banc appellate court directed a D.C. federal judge to hold further proceedings on Yemeni businessman and tribal leader Abdulsalam Al Abdulrahman Al-Hela's challenge to his detention at Guantánamo Bay, where he's been since 2004. The order's accompanying opinion wasn't immediately available Wednesday as it underwent a classification review.

The full court held, "assuming due process protections apply to Guantánamo detainees," the lower court correctly rejected al-Hela's due process challenge based solely on the length of his detention. But al-Hela's claim that his continued detention when he no longer presents an ongoing threat violates due process needs to be reconsidered, according to Tuesday's order.

Tuesday's ruling reverses part of an August 2020 panel opinion, authored by U.S. Circuit Judge Nemoi Rao, which found al-Hela was an enemy combatant with no ties to the United States who couldn't challenge his detention through procedural or substantive due process claims.

While the en banc D.C. Circuit agreed that al-Hela is an enemy combatant, it disagreed with Judge Rao's finding that he had no due process rights.

Tuesday's order showed Judge Rao partially dissented from the full court's opinion, but didn't explain which ruling she disagreed with.

Al-Hela filed his petition for writ of habeas corpus in D.C. federal court in 2005, arguing the Authorization for Use of Military Force underpinning the war on terror did not give the president authority to detain him indefinitely.

In 2019, however, Senior U.S. District Judge Royce C. Lamberth ruled that the AUMF allowed for the detention of those who "substantially supported" al-Qaida, even if they were not directly involved in hostilities against the United States or its allies.

Judge Lamberth found the government's intelligence reports alleging al-Hela helped transport fighters and secure fake identification documents were sufficient to stain him and that the due process clause doesn't apply to Guantánamo Bay detainees.

Al-Hela appealed Judge Lamberth's ruling to the D.C. Circuit in March 2019, arguing his indefinite detention was excessive and violated his substantive due process rights. He additionally claimed that evidentiary and discovery rulings by Judge Lamberth violated his procedural due process rights.

Judge Rao rejected both of those arguments in her August 2020 opinion. Relying on a line of D.C. Circuit precedent, the judge found the substantive due process clause doesn't apply to people outside the borders of the United States. She found procedural due process claims don't apply extraterritorially either.

Al-Hela requested en banc rehearing of his case in October 2020, arguing the panel's ruling conflicts with U.S. Supreme Court case law, and constituted an unprecedented determination that a person could be detained in Guantánamo Bay for simply supporting groups like al-Qaida.

The federal government responded in a December 2020 brief that there was no need to rehear al-Hela's case because he couldn't invoke the due process clause, and even if he could, his arguments are meritless, according to court documents.

The D.C. Circuit granted al-Hela's petition for en banc rehearing in April 2021 and heard oral arguments in the case in September 2021, according to court records.

A representative for the federal government declined to comment Wednesday, and counsel for al-Hela didn't immediately respond to requests for comment.

Al-Hela is represented by S. William Livingston, Robert A. Long, David M. Zionts and Andrew D. Garrahan of Covington & Burling LLP, and Beth D. Jacobs.

The U.S. is represented by Sharon Swingle and Brad Hinshelwood of the U.S. Department of Justice's Civil Division.

The case is Al-Hela v. Biden et al., case number 19-5079, in the U.S. Court of Appeals for the District of Columbia Circuit.

--Additional reporting by Daniel Wilson. Editing by Kristen Becker.