The U.S. Supreme Court has refused to hear an appeal from a Yemeni prisoner held without charge at Guantanamo Bay, Cuba for more than 17 years.

But Justice Stephen Breyer, in a two-page "statement" called attention to the case, declaring that it is "past time" to examine the indefinite detention of prisoners there.

"In my judgment," Breyer wrote, "it is past time to confront the difficult questions" left open.

Underlining the importance of the case was the fact that Justice Brett Kavanaugh recused himself. From 2006 until 2018, Kavanaugh served on the appeals court that has ruled on all the Guantanamo cases, the U.S. Court of Appeals for the District of Columbia.

Moreover, he served as a top aide to President George W. Bush when the Guantanamo detention policies were put in place. Both positions would seem to call for recusal, meaning that there are just eight current Supreme Court justices who could participate in Guantanamo appeals.

There are just 40 prisoners remaining at Guantanamo Bay, and just nine of them have been convicted of, or still face war crimes charges. Moath al-Alwi was captured by bounty hunters in Pakistan near the Afghanistan border in 2001 and turned over to the U.S. military. He has never been charged with any war crime. The U.S. government says he admitted to serving with the Taliban prior to his capture in 2001, but his lawyers maintain that he never used arms against American or coalition forces.

Since Guantanamo, known for short as Gitmo, was opened, some 780 prisoners have passed through its doors. Of these, 532 were released by the Bush administration, 197 by the Obama administration and one by the Trump administration. Five still at Gitmo have been recommended for release. Al-Alwi is among the remaining 26 being held under indefinite "law of war detention."

He appealed to the Supreme Court, contending that the U.S. government no longer has the authority to detain him without charge, because the conflict in which he was detained has, for all practical purposes, ended.

In addition, he claims that since there has never been any showing that he was engaged in combat against U.S. forces, holding him without charge in perpetuity is unconstitutional.

The high court declined to hear his appeal, but in its announcement on Monday, Justice Breyer attached a written "statement." In it, he noted that in the immediate aftermath of the Sept. 11, 2001 attacks, Congress passed the Authorization for Use of Military Force, known as the AUMF. It states that the president may "use all necessary and appropriate force against nations, organizations or persons he determines planned, authorized, committed or aided" those attacks.

But, Breyer observed, in 2004 the Supreme Court upheld the detentions at Guantanamo on "the understanding" that that enemy combatants were being held "for the duration of the relevant conflict."

Breyer noted that Justice Sandra Day O'Connor's plurality opinion cautioned that this understanding "may unravel" if the "practical circumstances" were to become "entirely unlike those of the conflicts that informed ... the law of war."

Indeed, she wrote, the "unconventional nature" of the war on terror presented a "substantial prospect" that detention for the "duration of the relevant conflict" could amount to "perpetual detention."

Whether such a perpetual detention would be legal under the laws of war and the AUMF, and whether it would be constitutional, were questions explicitly not decided by the court back then.

"The Government, represents that such hostilities are still ongoing [in Afghanistan]," Breyer wrote, "but does not state that any end is in sight."

He continued, "As a consequence, al-Alwi faces the real prospect that he will spend the rest of his life in detention based on his status as an enemy combatant a generation ago, even though today's conflict may differ substantially from the one Congress anticipated when it passed the AUMF."

In refusing to hear al-Alwi's appeal, the court "has taken no position" on the merits of his case, Breyer observed. But, he added, "I would, in an appropriate case," vote to hear an appeal "to address whether, in light of the duration and other aspects of the relevant conflict, Congress has authorized, and the Constitution permits continued detention."

President Obama tried to close Guantanamo in 2009, but Congress refused to appropriate the money to do that.

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