"The obligation to follow precedent begins with necessity, and a contrary necessity marks its outer limit. With Cardozo, we recognize that no judicial system could do society's work if it eyed each issue afresh in every case that raised it. See B. Cardozo, The Nature of the Judicial Process 149 (1921). Indeed, the very concept of the rule of law underlying our own Constitution requires such continuity over time that a respect for precedent is, by definition, indispensable. See Powell, Stare Decisis and Judicial Restraint, 1991 Journal of Supreme Court History 13, 16. At the other extreme, a different necessity would make itself felt if a prior judicial ruling should come to be seen so clearly as error that its enforcement was for that very reason doomed."
Planned Parenthood of Southeastern Pennsylvania v. Casey, 505 US 833 (1992).