I think what Capvin meant was he is not subject to other peoples system of punishment but answers to Congress I believe. He would have diplomatic immunity I think.
Try reading this link. It's not about the law of Canada or any other country but international law. And quite how Amnesty International would make money from the charges escapes my simple mind.
http://www.icc-cpi.int/Menus/ICC/About+the+Court/