Ottawa

Omar Khadr pulled the pin from a grenade and tossed it at Sgt. First Class Christopher Speer, a U.S. Army Delta Force medic, on July 27, 2002. Those are the facts to which Mr. Khadr, a Canadian citizen, confessed when he pleaded guilty before a Guantanamo Bay war-crimes commission.

For several years Mr. Khadr had been living and...