Abstract: In this Essay, Professor Richard Fallon explains and defends the constitutional status of stare decisis. In part, Professor Fallon responds to a recent article by Professor Michael Stokes Paulsen, who argues that Supreme Court adherence to precedent is a mere “policy,” not of constitutional stature, that Congress could abolish by statute. In particular, Paulsen argues that Congress could enact legislation denying precedental effect to Supreme Court decisions establishing abortion rights. In reply, Professor Fallon contends that Paulsen's argument depends on contradictory premises. If stare decisis lacked constitutional stature, then under Paulsen's methodological assumptions it also would be indefensible as a “policy,” because a mere policy could not legitimately displace results that the Constitution otherwise would require. In defending the constitutional status of stare decisis, Professor Fallon develops arguments based on the text, structure, and history of the Constitution. But he emphasizes that the “legitimacy” of stare decisis is supported, partly independently, by its entrenched status and by the contribution that it makes to the justice and workability of the constitutional regime. More generally, Professor Fallon argues that constitutional legitimacy rests upon the relatively contestable bases of widespread acceptance and reasonable justice, and not upon “consent” to be governed by the written Constitution.