The U.S. Supreme Court on Monday declined to wade into the contentious question of to what extent detainees held by the U.S. military at the American naval base at Guantanamo Bay, Cuba can seek their release, turning away an appeal by a Yemeni-born man held since 2001.


The court turned away an appeal by Yemeni detainee Moath Hamza Ahmed al Alwi, who was captured in Pakistan in December 2001 and detained without charge ever since. The U.S. government has said al Alwi was involved in fighting against U.S. and allied forces in Afghanistan and was closely linked with the Islamic militant group al Qaeda.


After the Sept. 11 2001 attacks on the United States, the United States began a long-running military campaign in Afghanistan targeting al Qaeda, which carried out the attacks, and the Taliban-led government that sheltered the group.


Justice Stephen Breyer, one of the court’s four liberals, issued a statement saying that the court should weigh in on the issue at some point to decide “whether, in light of the duration and other aspects of the relevant conflict, Congress has authorized and the Constitution permits continued detention.”


Al Alwi “faces that real prospect that he will spend the rest of his life in detention based on his status as an enemy combatant a generation ago,” Breyer added.


Al Alwi, who was born in 1977 and is in his early 40s, has said he should be released, in part because the U.S. conflict in Afghanistan has “effectively ended.” His lawyers have said that the authority of the United States to hold him has “unraveled” because of the length of the conflict. In a 2018 decision, the U.S. Court of Appeals for the District of Columbia Circuit rejected his claims.


The authority of the United States to hold al Alwi and other Guantanamo detainees is based on the 2001 authorization for use of military force that Congress approved in the aftermath of the Sept. 11 attacks.


In 2014, then-President Barack Obama declared an end to combat operations in Afghanistan, but the Justice Department said in court papers that “active hostilities continue.” Peace talks between the U.S. and the Taliban are ongoing.


The Supreme Court heard several Guantanamo cases soon after the conflict began, but the last ruling came in 2008. The court ruled then that the prisoners had a legal right to go before a judge in challenging the legality of their detention and in seeking their release. In the past decade, the court has repeatedly rejected subsequent appeals from detainees.


Al Alwi’s previous attempt to seek his release failed in lower courts.