Scholars of comparative constitutional law would suggest that the United States Constitution is the world’s most difficult democratic constitution to change by formal amendment. But in this paper I suggest that the Constitution of Canada may be even harder to amend. Modern Canadian political history has proven the textual requirements for major constitutional amendment so far impossible to satisfy, yet the extraordinary difficulty of formal amendment in Canada derives equally from sources external to the Constitution’s formal amendment rules. Major constitutional amendment also requires conformity with extra-textual requirements imposed by Supreme Court decisions interpreting the Constitution of Canada, parliamentary and provincial as well ...