A appeals court  in Washington, D.C., on Friday ruled that Khalid Sheikh Mohammed, the accused mastermind of the 9/11 attacks, and two of his co-defendants, could not plead guilty under agreements that would have spared them the death penalty.

Those plea agreements had sparked anger among some relatives of victims of the September 11, 2001 attacks. 

They been offered last year and accepted by the official who oversees the Pentagon's Guantanamo war court, but then US defense secretary, Lloyd Austin, moved to revoke it, saying that both the relatives and the American public deserved to see the defendants stand trial.

Attorneys for the defendants had argued that the agreement was already legally in effect and that Austin, who served under President Joe Biden, acted too late to try to throw it out.

Austin "acted within the bounds of his legal authority, and we decline to second-guess his judgment,"  judges Patricia Millett and Neomi Rao wrote.

What was Austin's argument?

The please deals, negotiated over two years and approved by military prosecutors and the Pentagon's senior official for Guantanamo Bay, Cuba, stipulated life sentences without parole for Mohammed and two co-defendants.

It seemed to have propelled their cases toward an end after years of being weighed down in pre-trial maneuverings while the defendants remained held at the Guantanamo Bay Prison Camp in Cuba

But Austin stepped in, and withdrew the arrangements two days after they were announced. He argued the decision should be up to him, given its significance.

Austin subsequently said that "the families of the victims, our service members and the American public deserve the opportunity to see military commission trials carried out in this case."

A military judge, however, ruled that Austin lacked the authority to take on such a decision. This was then upheld in December by US Court of Military Commission Review. The judge then scheduled prompt plea hearings.

But Friday's ruling would now appear to reverse that decision once more.

What did the judges say?

US Circuit Judges Patricia Millett and Neomi Rao, who backed the new ruling among a divided panel, said Austin "indisputably had legal authority to withdraw from the agreements."

"Having properly assumed the convening authority, the Secretary determined that the 'families and the American public deserve the opportunity to see military commission trials carried out," the judges wrote. "The secretary acted within the bounds of his legal authority, and we decline to second-guess his judgment."

In a dissent, Judge Robert Wilkins, found, "The government has not come within a country mile of proving clearly and indisputably that the Military Judge erred."

Brett Eagleson, who was among the family members who objected to the deal, called Friday's appellate ruling "a good win, for now."

Edited by: Louis Oelofse