I would like to go one step further and explain exactly how the U.S codifies that exception.
As Mr. Arnold has just stated, the United States drew up a list of states which, in its view, support terrorism. Today there are four states on that list. They are Cuba, Iran, Sudan and Syria. Not so long ago, North Korea, Libya and Irak were also on the list, but those three countries have since been removed. The United States has normalized its relations with these countries. So, those four countries are listed. There are a number of consequences associated with that designation, including a denial of immunity for civil proceedings launched only by U.S. citizens. No remedy is available to foreigners who have been tortured outside of the United States. Only U.S. citizens have access to that remedy whereby immunity is refused. It is a very limited mechanism, as well as being a highly problematic one.
If you are asking my professional opinion, I would say this is not something that Canada should consider doing. Canada should take a position that relies more on international law and is more respectful of the general principles of international law.