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.
