Stare decisis

Stare decisis requires courts to give weight to earlier judicial decisions when deciding later cases involving similar legal issues. The strongest form is vertical precedent: lower courts ordinarily must follow controlling decisions of higher courts in the same judicial hierarchy. Horizontal precedent concerns a court’s treatment of its own earlier decisions and is usually less rigid, particularly in a supreme or constitutional court.¹

Precedent does not mean that every statement in an earlier opinion binds later courts. The controlling element is generally the ratio decidendi, or legal rule necessary to the result. Observations not essential to the judgment, often called obiter dicta, may be persuasive without possessing the same force. Courts also examine the material facts, the scope of the holding, and the level of the court that issued it.

Stare decisis serves predictability, equal treatment, efficient adjudication, and the institutional legitimacy of courts. People, businesses, legislatures, and public agencies can organize conduct around established interpretations instead of relitigating the same legal question in every case. The doctrine can also restrain individual judges by placing legal reasoning within an accumulated body of decisions.²

Precedent is not absolute. Courts may distinguish an earlier case when legally relevant facts differ, narrow a holding that has proved too broad, or reject an earlier rule under the conditions permitted by the relevant legal system. The United States Supreme Court has described factors relevant to overruling precedent, including the quality of the earlier reasoning, workability, reliance interests, changed legal or factual circumstances, and the consistency of the rule with related doctrine.³

Stare decisis is closely associated with common-law adjudication, in which reported judicial decisions help develop legal rules alongside legislation and custom. Its modern form developed gradually rather than appearing as a single, fully defined command. The doctrine is particularly influential in jurisdictions such as England and Wales, the United States, Canada, Australia, and New Zealand, although each has its own hierarchy, rules of precedent, and methods for departing from earlier decisions.

Courts preserve flexibility through techniques such as distinguishing, overruling, reversing, and refusing to extend a precedent. A decision may be reversed on appeal in the same litigation, while overruling usually means that a later court rejects the legal rule of an earlier case. Legislative enactments can also replace or modify judge-made rules, subject to constitutional limits and rules governing retroactivity.

Stare decisis does not always require a court to preserve a mistaken rule indefinitely. A precedent may lose force when later decisions undermine its reasoning, when technological or social conditions change the practical effects of the rule, or when its application creates unmanageable distinctions. Yet courts often demand a particularly strong justification before abandoning precedent in areas involving property, contracts, criminal procedure, or other substantial reliance interests.⁴

The doctrine also operates differently in constitutional and statutory cases. Constitutional precedent can be difficult to correct through ordinary legislation, while statutory precedent may be displaced by a clear legislative amendment. In some legal systems, courts publish judgments with separate opinions, making competing rationales visible and complicating the task of identifying the precise rule that later courts must follow. International courts and tribunals may treat prior decisions as persuasive rather than strictly binding.⁵

Precedent

An earlier judicial decision or legal rule used to guide the determination of a later case.

Ratio decidendi

The legal reasoning or rule necessary to the judgment, as distinct from incidental observations.

Obiter dicta

Statements in a judicial opinion that are not necessary to the decision and generally have persuasive rather than binding force.

Overruling

A later court’s rejection of the legal rule established by an earlier decision.

Distinguishing

Treating an earlier precedent as inapplicable because legally significant facts or issues differ.