In a decision that will likely make it more difficult for Guantanamo prisoners to win release, the U.S. Court of Appeals for the D.C. Circuit today reversed a lower court’s ruling in the pivotal case of a Yemeni detainee.

In a 14-page decision, the appeals court rejected the lower court’s ruling to release Uthman Abdul Rahim Mohammed Uthman, who has been held at Guantanamo without charge since 2002. Uthman’s case and the government’s attempts to classify the legal opinions it generated were the subject of a ProPublica story.

The appeals court standard for detention has been laid out over the last year in a number of significant cases, and as with today’s case, each time in the government’s favor. The results have been a boon for the Obama administration’s efforts to keep certain Guantanamo detainees in custody.

Today’s decision further clarifies that standard by declaring that the government doesn’t need direct evidence that a detainee fought for or was a member of al-Qaida in order to justify a detention.

Much was riding on the Uthman case because he is among several dozen prisoners the Obama administration plans to hold indefinitely without charge. For other detainees, it will likely alter the way they can present their cases for release.

In 2008, Guantanamo detainees won the right to challenge the lawfulness of their detention in court. The first challenges were largely successful for detainees, but a number of significant cases have been pushed back at the circuit court.

Uthman filed a challenge, and in February 2010, District Court Judge Henry H. Kennedy, Jr. ruled that he was being improperly held and that the United States had failed to demonstrate that he was a member of al-Qaida. As ProPublica detailed, the government censored Kennedy’s decision and quickly appealed the case to a court that was already lowering the government’s burden for proving a prisoner’s detainability.

In another case last year, known as Salahi, the appeals court rejected a lower court’s standard that the government show direct evidence the detainee was a member of al-Qaida. In that case, the court sent the detainee back to the district court to have his habeas corpus petition reheard.

In today’s opinion, written by Judge Brett Kavanaugh, the appeals court went further by reversing the habeas win outright. In doing so, the court determined that circumstantial evidence, such as a detainee being in the same location as other al-Qaida members, is enough to meet the standard to hold a prisoner without charge.

That standard, the court wrote in its decision today, “along with uncontested facts in the record, demonstrate that Uthman more likely than not was part of al Qaeda.”

Benjamin Wittes of the Brookings Institution and the national security blog Lawfare attended Uthman’s appeals hearing in February and predicted that the government would prevail. Noting the circuit court’s emerging standards, Wittes wrote that if the appeals court ordered an outright reversal of the Uthman decision “a lot of other Guantanamo detainees are going to share his pain. His case could end up lowering the substantive bar for the government to prevail in these habeas cases.”

Jonathan Hafetz, a professor at Seton Hall University School of Law who has represented a number of Guantanamo detainees including Salahi, said today’s opinion significantly favors the government in ways the Supreme Court did not intend when it granted detainees the right to challenge detentions.

“The Uthman case cements the trend in the D.C. Circuit's decisions toward a broad and malleable definition of who can be considered ‘part of’ al Qaeda, combined with a highly deferential view of the government's interpretation of the facts,” Hafetz said, “In many cases, the result is indefinite detention based on suspicion or assumptions about a detainee's behavior.”

Hafetz argued that today’s decision conflicts not only with the approach taken by the district courts but also with the Supreme Court. Hafetz said the Supreme Court “mandated a meaningful judicial process in which the government would be called to account; Uthman says judges should not require much in the way of an answer.”

Wittes embraced today’s opinion, writing on his blog that the court’s opinion reflects the complex reality of Guantanamo Bay. Today’s case asks “whether a relatively spare string of incriminating facts can get the government over the hump. The answer now is clear: It can,” Wittes wrote.

“Many fewer detainees will prevail under this understanding of the government’s evidentiary burden than would prevail under one less tolerant of a mosaic of incriminating facts,” he wrote.