Supreme Court Blocks 9/11 Plea Deal Revival as Alleged Mastermind Khalid Sheikh Mohammed Faces Death Penalty Risk

The US Supreme Court on Monday rejected a bid to revive plea agreements that would have spared Khalid Sheikh Mohammed, the alleged mastermind of the 11 September 2001 attacks, and two co-defendants the death penalty, leaving the government free to pursue capital charges in a case that has remained unresolved for more than two decades.

The unsigned order leaves intact a July 2025 ruling by a federal appeals court upholding former US defence secretary Lloyd Austin's decision to cancel the agreements in August 2024. The deals would have required the three men to plead guilty in exchange for the government agreeing not to seek their execution. The justices did not explain declining to hear the appeal. Justice Brett Kavanaugh took no part in the decision.

Court Upholds Austin's Authority to Cancel Deals

The agreements were accepted on 31 July 2024 by Susan Escallier, a retired US Army brigadier general who served as the convening authority overseeing military commissions at Guantánamo Bay, the US naval base in Cuba where terrorism suspects have been detained since 2002. On 2 August 2024, Austin, who served as defence secretary under President Joe Biden, withdrew the government from the deals.

The cancellation triggered a dispute over who had the authority to approve the agreements. Military judges initially ruled that Austin could not reverse them, allowing proceedings to move towards the entry of guilty pleas. The government challenged those decisions before the US Court of Appeals for the District of Columbia Circuit, a civilian federal appeals court.

In a 2-1 decision on 11 July 2025, the appeals court ruled that Austin had the legal authority to withdraw from the agreements. The majority found that the defendants had not begun performing the obligations set out in the deals before Austin intervened. The Trump administration continued to defend the cancellation, and the Supreme Court's refusal to hear the appeal leaves that ruling in force.

Four Defendants Face Provisional 2028 Trial Date

The capital case involves four men: Mohammed, Walid bin Attash, Mustafa al-Hawsawi and Ali Abdul Aziz Ali, also known as Ammar al-Baluchi. The plea agreements covered only the first three; al-Baluchi did not join the deals. All four face charges connected to the attacks, which killed 2,977 people when hijacked planes struck the World Trade Center and the Pentagon, while a fourth aircraft crashed in Pennsylvania.

Air Force Lt Col Michael Schrama, the military judge, set 5 June 2028 as the provisional start date for the trial at Guantánamo Bay on 26 August, rejecting prosecutors' proposal of January 2027. The timetable remains uncertain because disputes over evidence gathered during earlier CIA interrogations continue to complicate the proceedings. The judge ruled that prosecutors could not use an alleged confession Mohammed made to the FBI in 2007, finding it tainted by his treatment in CIA custody, including waterboarding. The government decided not to appeal.

The proceedings have been delayed by litigation over the military commissions' authority, the treatment of detainees and the admissibility of evidence. The Supreme Court's order resolves the latest challenge to the plea agreements, but it does not settle those separate questions or determine the defendants' guilt.

Plea Agreements Divided 9/11 Victims' Families

The proposed deals divided relatives of those killed in the attacks. Some opposed a negotiated resolution and wanted the defendants to face trial, with the possibility of death sentences. Others backed the agreements as a route to guilty pleas, public admissions and answers about the attacks after years of pretrial proceedings.

September 11th Families for Peaceful Tomorrows, an organisation of relatives of victims that advocates non-violent approaches to conflict, urged the Supreme Court to hear the appeal. The group supported restoring the agreements, which would have required the defendants to admit their guilt and accept life sentences. The arrangements also offered a framework for victims' relatives to address the men during sentencing proceedings.

The charges were brought in 2012, and the case has yet to reach a full trial. Steve Vladeck, a Georgetown law professor who filed a friend-of-the-court brief urging the justices to take the case, said the denial paves the way for the ongoing pretrial process, but described the 2028 trial date as unrealistic given the number of unresolved issues, according to CNN.