Well, the difference is more textual than customary in the case of Canada. The Canadian Charter of Rights and Freedoms is explicit (as opposed to the U.S. Bill of Rights) in laying out exceptions to free speech rights. I originally found this to be something like heresy, responding to Jeremy’s point about undue reverence to the Constitution. Eventually, I realized the Canadians had done a good job, and the U.S. Constitution isn’t sacred writ.