Nathan Whitling appeared in court Thursday on behalf of the teen, who was arrested last month on allegations he was planning to leave Canada to fight with Islamic State militants.
The youth, who cannot be identified, said nothing as he stood on closed circuit TV broadcast in an Edmonton courtroom.
He was remanded in custody and his next court date was set for April 20.
Whitling wouldn't discuss the case with reporters and told court he's waiting for more disclosure on the case from the federal Crown.
RCMP arrested the Alberta teen in Beaumont, a bedroom community south of Edmonton.
He faces two charges — attempting to leave the country to participate in a terrorist group and attempting to leave the country to commit a terrorist activity, "namely murder."
Khadr, born in Toronto, was 15 when he allegedly killed an American soldier in Afghanistan and was imprisoned in Guantanamo Bay.
After spending nearly a decade in the detention camp, he was sentenced by a U.S. military commission to an additional eight years and transferred to Canada to complete his sentence.
He has since claimed he pleaded guilty only to get out of Guantanamo and is appealing the conviction to a U.S. military court.