Abstract: Most jurists and scholars today take for granted that the U.S. Constitution imposes unwritten but judicially enforceable limits on how Congress and the President may construct their interrelationships by statute. This “juristocratic” understanding of the separation of powers is often regarded as a given or inherent feature of American constitutionalism. But it is not. Instead, it emerged from a revanchist reaction to Reconstruction. As an ascendent white South violently returned to power in Washington, its intellectual supporters depicted a tragic era in which an unprincipled Congress unconstitutionally paralyzed the President in pursuit of an unwise and unjust policy of racial equality. Determined to prevent Reconstruction from reoccurring, historians, political scientists, and a future Supreme Court Justice by the name of William Howard Taft demanded judicial intervention to prevent Congress from ever again weaving obstructions around the President. This Lost Cause dogma became Supreme Court doctrine in Myers v. United States. Authored by Chief Justice Taft, the opinion was the first to condemn legislation for violating an implied legal limit on Congress’s power to structure the executive branch. It is today at the heart of an ongoing separation-of-powers counterrevolution. That counterrevolution has obscured, and eclipsed, a more normatively compelling conception of the separation of powers—one that locates in representative institutions the authority to constitute the separation of powers by statute. This “republican” conception accepts as authoritative the decision of the political branches as to whether a bill validly exercises the Necessary and Proper Clause to carry into execution the powers and interrelationships of Congress, the President, and the executive branch. Where the juristocratic separation of powers undermines both the legal legitimacy of the Court and the democratic legitimacy of the political branches, the republican separation of powers sustains an inherently provisional constitutional order—one grounded in deliberation, political compromise, and statecraft.