The Obama administration tried on Monday to salvage a military tribunal's conviction of Osama bin Laden's publicist, the latest case to underscore the legal troubles surrounding the tribunal system at the Guantanamo Bay U.S. Naval Base in Cuba.
Justice Department lawyer Ian Gershengorn urged a U.S. appeals court at a hearing in Washington to affirm the conviction of Ali Hamza al Bahlul, the former publicist and videographer for the al Qaeda leader.
Bahlul is serving a life sentence at Guantanamo after a tribunal in 2008 convicted him of conspiracy, material support for terrorism and solicitation of others to commit terrorism.
But the Yemeni's conviction was overturned in January by a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit, which ruled that the three charges were not internationally recognized as war crimes when Bahlul allegedly committed them and could not be prosecuted in a military tribunal.
That ruling and a similar one in the case of bin Laden's former driver, Salim Hamdan, raised legal havoc.
The Obama administration originally planned to try 36 Guantanamo prisoners in tribunals, in addition to three tried during the George W. Bush administration.
Amid concerns about the conspiracy and material-support charges, the plans were scaled back and prosecutors planned to try 20 Guantanamo detainees at most, including seven already tried.
The detention camp houses 164 prisoners. U.S. officials say 46 are too dangerous to release but cannot be put on trial because of a lack of evidence. They are facing indefinite detention without charges. The administration wants to repatriate most of the rest, or transfer them to third countries if Congress allows and if U.S. officials can find other countries to take them.
Hamdan was transferred home to Yemen in 2008 and released to live with his family the next year.
In April prosecutors asked the full, seven-judge D.C. Circuit court to take another look at the theory in Bahlul's case and affirm his conviction.
The appeals court considers most cases in panels of three judges but heard it as a seven-judge court, in a signal of the importance of Bahlul's case. It could rule at any time.
Gershengorn told the court that American common law has a long history of military prosecutors charging people with conspiracy, from President Abraham Lincoln's 1865 assassination to German saboteurs during World War Two.
"The backdrop is an evolving, common law system," he said.
The judges stopped short of committing themselves to a side but asked skeptical questions of Gershengorn while running out of things to ask Bahlul's lawyer, Michel Paradis.
Paradis cited counter-examples of U.S. judges refusing to consider conspiracy charges under the international law of war because the term "conspiracy" is so broad.
None of the three charges against Bahlul was rooted in clearly established law, he said. Even if they could be crimes under the law governing the Guantanamo tribunals, the Military Commissions Act of 2006, the law could not apply retroactively to earlier conduct, he said.
"My client cannot be convicted of crimes that did not exist when he is alleged to have committed them," said Paradis, a U.S. military defense lawyer.
One aspect of the case - whether the military could bring at least some of the charges under a 2006 law rather than under the international law of war - was a "close call," said Judge Thomas Griffith.
Judge Merrick Garland cast doubt on the validity of material-support charges, quoting to Gershengorn a public statement from a top Pentagon lawyer that it was "questionable" whether the charges could stand up.
Regardless of the outcome, the U.S. military is not expected to free Bahlul from Guantanamo. It could pursue different charges against him or detain him indefinitely, a power the U.S. government claims as part of its war against al Qaeda.
"It's not a release order" if Bahlul wins the case, Judge Brett Kavanaugh told Gershengorn, who agreed. Kavanaugh wrote an October 2012 ruling that overturned the Guantanamo conviction of Hamdan.
President Barack Obama has pressed forward with military tribunal trials in the hope that they will add legal validity to the ongoing detentions while he tries to persuade Congress to close the prison.
The case is Ali Hamza al Bahlul v. United States, U.S. Court of Appeals for the D.C. Circuit, No. 11-1324.