The US Supreme Court on Tuesday refused an appeal bid by one of Guantanamo's most famous detainees, backing the legitimacy of the special military courts in place at the US naval base in Cuba.
The decision confirms the life sentence handed to Ali Hamza Ahmad al-Bahlul, a lieutenant of Osama bin Laden, and held in Guantanamo since 2002.
The Yemeni, identified as the former propagandist of al-Qaeda, appealed his conviction in 2008 for criminal conspiracy.
According to his lawyers, this charge should have been brought before a federal civil court and not a military court.
The Supreme Court move is good news to Donald Trump's administration. He has spoken in favor of resorting more to using Guantanamo facilities and courts.
A number of men suspected of involvement in the September 11, 2001 attacks are still awaiting trial on the US base.
In an important decision called "Boumediene vs Bush," the US Supreme Court in 2008 allowed Guantanamo detainees to challenge the validity of their detention before American civil courts.
But the Supreme Court has since refrained from widening the scope for questioning the actions of the Guantanamo court.