That is to say, the effectiveness of Constitutional Law as a system of restraints on governmental action in the United States, which is its primary _raison d'etre_, depends for the most part on the effectiveness of these doctrines as they are applied by the Court to that purpose. The doctrines to which I refer are (1) the doctrine or concept of Federalism; (2) the doctrine of the Separation of Powers; (3) the concept of a Government of Laws and not of Men, as opposed especially to indefinite conceptions of presidential power; (4) and the substantive doctrine of Due Process of Law and attendant conceptions of Liberty. What I proposed to do is to take up each of these doctrines or concepts in turn, tell something of their earlier history, and then project against this background a summary account of what has happened to them in recent years in consequence of the impact of war, of economic crisis, and of the political and ideological reaction to the latter during the Administrations of Franklin D. Roosevelt. I Federalism Federalism in the United States embraces the following elements: (1) as in all federations, the union of several autonomous political entities, or "States," for common purposes; (2) the division of legislative powers between a "National Government," on the one hand, and constituent "States," on the other, which division is governed by the rule that the former is "a government of enumerated powers" while the latter are governments of "residual powers"; (3) the direct operation, for the most part, of each of these centers of government, within its assigned sphere, upon all persons and property within its territorial limits; (4) the provision of each center with the complete apparatus of law enforcement, both executive and judicial; (5) the supremacy of the "National Government" within its assigned sphere over any conflicting assertion of "state" power; (6) dual citizenship.