Montesquieu may be a better guide to understanding the nature of the Canadian state, past and present, than Hobbes or Locke of any of the other political philosophers of the past. This article argues that Montesquieu's doctrine has two major components–a discussion of the mixed constitution, blending monarchical, aristocratic and democratic features, and the separation of powers that distinguishes among executive, legislative and judicial. Each of these components can be used to illuminate the operation of state power at the central level in this country, the first the long period between 1867 and the Second World War, the second the post-Second World War period, and more especially the situation that has arisen with the passage of the Constitution Act, 1982.