Updated

A federal appeals court on Monday set aside two of three convictions against a former personal assistant to Osama bin Laden.

The U.S. Court of Appeals for the District of Columbia Circuit issued the ruling in the case of Ali Hamza al Bahlul, who produced propaganda videos for al-Qaida and assisted with preparations for the terrorist attacks of Sept. 11, 2001.

A military commission had convicted him of conspiracy to commit war crimes, providing material support for terrorism and soliciting others to commit war crimes. He has been sentenced to life imprisonment.

The appeals court rejected Bahlul's challenge to his conspiracy conviction, but overturned his material support and solicitation convictions.

The court, in an opinion by Judge Karen LeCraft Henderson, said the government had offered little backup for the notion that a military commission could try defendants on the charges for which the convictions were overturned — material support for terrorism and solicitation to commit war crimes.

On the third charge, the appeals court said Congress has positively identified conspiracy as a war crime.

Since the Guantanamo Bay detention center opened at the U.S. Navy base in January 2002, eight prisoners have been convicted of war crimes. One of those cases was overturned by a civilian court and six came through plea bargains. Six others are facing trial, including the five men charged in the Sept. 11 attacks.

Human Rights First, a nonprofit group, said the decision highlights the problems of continuing to rely on military commissions to handle such cases.

"There is no question that al Bahlul could have been tried in a U.S. federal court on terrorism-related charges and justice would have been served long ago," said Daphne Eviatar, senior counsel of the law and security program at Human Rights First.