Lawyers for Canadian Omar Khadr want a U.S. military judge to dismiss his terrorism case on the grounds that he was a child soldier when he was captured in Afghanistan in 2002.
They've filed a motion arguing that a military tribunal has no jurisdiction over Khadr because he was 15 years old when he allegedly threw a grenade that killed a U.S. soldier.
The motion contends that trying Khadr at the U.S. naval base in Guantanamo Bay would violate international law.
It is one of several motions being filed on behalf of Khadr, who's charged with murder in the 2002 death of American medic Sgt. First Class Christopher J. Speer in Afghanistan. He is also charged with spying, conspiracy and supporting terrorism.
Another motion argues the war crimes system set up by U.S. President George W. Bush to try terror suspects is unconstitutional because it was designed only for non-Americans.
Some of the defence motions are expected to be considered at a hearing next month.