The U.S. Supreme Court on Monday rejected an appeal by accused September 11 mastermind Khalid Sheikh Mohammed and two alleged co-conspirators seeking to reinstate plea agreements that would have taken the death penalty off the table, removing another legal hurdle to their long-delayed military trial.
The justices declined to review appeals involving Mohammed and his co-defendants, Mustafa al-Hawsawi and Walid bin Attash. The decision leaves intact a federal appeals court ruling that upheld former Defense Secretary Lloyd Austin’s authority to withdraw the agreements.
As is customary when rejecting petitions for review, the Supreme Court offered no explanation. The decision leaves the lower court’s ruling in place but does not necessarily signal that the justices endorsed every aspect of its reasoning.
Dispute Over the 2024 Plea Agreements
In July 2024, the three defendants reached agreements with military prosecutors under which they would plead guilty to charges related to the September 11, 2001, terrorist attacks in exchange for the government abandoning its pursuit of the death penalty.
The agreements would have resulted in life imprisonment without the possibility of parole, potentially bringing portions of a military prosecution that has dragged on for more than two decades closer to a conclusion.
However, Austin intervened just two days after the agreements were approved, withdrawing them on the grounds that a decision of such magnitude, particularly one involving the death penalty, should rest with the defense secretary.
His move triggered another legal battle over whether he had the authority to cancel agreements already accepted by the Pentagon official overseeing the Guantanamo military commissions.
A military judge initially ruled in favor of the defendants, finding that Austin could not rescind the agreements at that stage. The U.S. Court of Military Commission Review subsequently allowed that decision to stand.
The government then challenged those rulings in federal court.
In July 2025, a divided three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit sided with the government in a 2-1 decision. The appeals court concluded that Austin “indisputably had legal authority to withdraw from the agreements,” rejecting arguments that his intervention came too late.
Mohammed and al-Hawsawi later appealed to the Supreme Court, arguing that Austin’s actions violated military law and further prolonged an already lengthy prosecution.
Monday’s decision leaves the appeals court ruling intact, allowing prosecutors to continue pursuing capital charges against the defendants.
The Charges Against the Alleged 9/11 Plotters
Mohammed is accused of masterminding the September 11 attacks, in which al Qaeda operatives hijacked four commercial passenger planes. Two aircraft struck the World Trade Center in New York City, another hit the Pentagon, and the fourth crashed in Pennsylvania after passengers and crew attempted to regain control.
Nearly 3,000 people were killed in the attacks, which prompted the U.S. war in Afghanistan and dramatically transformed American national-security policy.
Mohammed was captured in Pakistan in 2003 after years of pursuing al Qaeda leaders. He was held in secret CIA detention facilities before being transferred to the U.S. detention center at Guantanamo Bay, Cuba, in 2006.
The prosecution has repeatedly been delayed by disputes over classified evidence, the legal framework governing military commissions and questions surrounding statements obtained during CIA interrogations, including techniques widely criticized as torture.
These complications have made the case one of the most protracted and legally contentious prosecutions arising from the September 11 attacks.
Families of 9/11 Victims Divided Over the Deals
The proposed plea agreements generated sharply differing reactions among families of those killed on September 11.
Some relatives opposed the deals, arguing that eliminating the possibility of execution would deny them the harshest available punishment for those accused of participating in the attacks.
Others supported the agreements, viewing guilty pleas as a potential way to secure accountability and bring a case that has remained unresolved for decades closer to an end.
Republican lawmakers also condemned the agreements when they were announced in 2024, objecting to any arrangement that would remove the death penalty from a prosecution involving the deadliest terrorist attack in American history.
The controversy highlighted the difficult balance between pursuing the harshest possible punishment, securing convictions and finally resolving a case burdened by years of legal disputes.
Trial Still Years Away
Despite Monday’s Supreme Court decision, the case remains far from resolution.
The ruling does not guarantee that the defendants will be convicted or sentenced to death. Prosecutors must still establish their cases through the military commission system, and any capital sentence would depend on the outcome of those proceedings.
The defendants are currently scheduled to stand trial in June 2028, following a timetable established by an Air Force judge earlier this year. Further pretrial litigation could still affect that date.
For now, however, the government has secured a significant legal victory. The Supreme Court’s refusal to intervene leaves the Pentagon’s cancellation of the plea agreements in place and preserves prosecutors’ ability to seek the death penalty against the three defendants.
After more than two decades of delays, the ruling marks another major development in the effort to bring the September 11 prosecutions to trial, even as substantial legal obstacles remain.