The U.S. Supreme Court declined to reconsider a plea agreement for Khalid Sheikh Mohammed and two other suspects accused of orchestrating the Sept. 11, 2001, terrorist attacks, allowing the possibility of a death penalty trial to proceed. The court’s decision was issued Monday as part of a routine orders list, without explanation or noted dissents. Justice Brett Kavanaugh did not participate in the ruling, having previously served on the U.S. Court of Appeals for the District of Columbia Circuit, where he handled cases related to detainees held at Guantánamo Bay.

Mohammed, widely regarded as the mastermind behind the attacks that killed nearly 3,000 people, has been detained at the U.S. naval base in Guantánamo Bay since 2006. The other two defendants in the appeal, Mustafa al-Hawsawi and Walid bin Attash, are accused coconspirators.

The plea deal, authorized by a senior Defense Department official in 2024, would have resolved the case without pursuing the death penalty, instead imposing life sentences. In exchange, the defendants would have relinquished their right to appeal. However, the agreement faced immediate criticism and was rescinded days later by Defense Secretary Lloyd Austin, reopening the path toward a potential capital punishment trial.

Although a military judge initially allowed the plea agreements to proceed, a federal appeals court upheld Austin’s revocation of the deal. Defense attorneys then petitioned the Supreme Court to intervene, emphasizing the national significance of the case and asserting that appeals courts were divided on key procedural issues.

Representing the government, Solicitor General D. John Sauer urged the court to decline involvement, arguing that the appeals court had correctly addressed serious legal errors made by the military judge. Sauer noted the complexity of the prosecution, acknowledged differing opinions among victims' families regarding the death penalty, and contended that Supreme Court intervention was unnecessary at this stage.

The forthcoming trial, scheduled by the current military judge to begin June 5, 2028, is expected to last over a year. Despite the Supreme Court’s decision clearing one significant hurdle, additional pretrial litigation remains. Central to the ongoing legal challenges are disputes over the admissibility of confessions allegedly obtained through coercive interrogation techniques at Guantánamo Bay in 2007 and 2008.

The case continues to represent one of the most complex and prolonged prosecutions in U.S. history, reflecting the legal and ethical difficulties involved in addressing acts of terrorism while balancing national security and fair trial considerations.