Precedent

Precedent is a judicial decision that serves as an authority for courts when deciding subsequent identical or similar cases. Fundamental to common law legal systems, precedent operates under the principle of stare decisis ("to stand by things decided"), where past judicial decisions serve as case law to guide future rulings, thus promoting consistency and predictability.

Precedent is a defining feature that sets common law systems apart from civil law systems. In common law, precedent can either be something courts must follow (binding) or something they can consider but do not have to follow (persuasive). Civil law systems, in contrast, are characterized by comprehensive codes and detailed statutes, with little emphasis on precedent (see jurisprudence constante), and where judges primarily focus on fact-finding and applying the codified law.

Courts in common law systems rely heavily on case law, which refers to the collection of precedents and legal principles established by previous judicial decisions on specific issues or topics. The development of case law depends on the systematic publication and indexing of these decisions in law reports, making them accessible to lawyers, courts, and the general public.

Generally speaking, a legal precedent may be:

applied (if precedent is binding) / adopted (if precedent is persuasive), if the principles underpinning the previous decision are accordingly used to evaluate the issues of the subsequent case;

distinguished, if the principles underpinning the previous decision are found specific to, or premised upon, certain factual scenarios, and not applied to the subsequent case because of the absence or material difference in the latter's facts;

modified, if the same court on determination of the same case on order from a higher court modified one or more parts of the previous decision; or

overruled, if the same or higher courts on appeal or determination of subsequent cases found the principles underpinning the previous decision erroneous in law or overtaken by new legislation or developments.

Principles

Stare decisis

Stare decisis () is a judicial doctrine under which courts follow the principles, rules, or standards established in their prior decisions (or those of higher courts) when deciding cases involving the same or closely related issues. The term originates from the Latin phrase stare decisis et non quieta movere, meaning to "stand by the thing decided and do not disturb the calm."

The doctrine operates both horizontally and vertically.