Abstract: This chapter probes the doctrine of stare decisis as it functions in constitutional cases in the Supreme Court of the US. It solves what some have viewed as two puzzles about constitutional stare decisis in the US. One involves how past decisions that the justices believe to be erroneous can displace the original meaning of a constitution that purports to be ‘the supreme law of the land’. The other mystery is how it can be that if erroneous precedents sometimes prevail over the US Constitution’s original meaning, they do not always do so. In response to the first puzzle, this chapter appeals to the Hartian concept of a ‘rule of recognition’, grounded in official practice and ‘acceptance’. In addressing the second puzzle, this chapter relies on Hart’s distinction between rules of recognition and ‘rules of change’. In the Supreme Court, the chapter argues, an important practical function of the doctrine of stare decisis is to empower the justices to act as constitutional law-makers choosing whether to effect or not to effect legal change. In addition to clarifying the role of constitutional stare decisis in the Supreme Court, this chapter seeks to advance understanding of possible variations in the functioning of stare decisis in different legal systems and of Hartian jurisprudential concepts, including those of rules of recognition and rules of change.