Lawyers for Canadian Omar Khadr have filed an appeal with the U.S. Court of Appeals to try to stop the legal case against him from proceeding.
Military lawyer Cmdr. William Kuebler said a special military appeals court was wrong last month when it said the case could go ahead in Guantanamo Bay.
At issue is the fact that Khadr hasn't been designated an illegal enemy combatant as required by Congress.
Kuebler also argues that the murder trial at the U.S. naval base in Cuba wouldn't allow him to raise key issues of international and constitutional law.
Khadr, now 21, was 15 years old when he allegedly threw a grenade that killed a U.S. medic in a 2002 firefight in Afghanistan.
Khadr's military commission is scheduled to resume Nov. 8.