decidendi

Decidendi is a Latin term used in jurisprudence to refer to the ground or reasoning on which a court's decision rests. In common usage it is closely associated with ratio decidendi, the essential rule of law that emerges from a case and binds future decisions.

Etymology and usage: Decidendi comes from the Latin verb decidere, meaning to decide, with the gerundive form meaning “of deciding.” In a judgment, the decidendi is the part that explains why the decision was made and what legal principle it applies. It is distinct from other statements in the same decision that are not necessary to decide the outcome.

Distinction from obiter dicta: Obiter dicta are remarks made by judges in the course of delivering a judgment that are not essential to the decision. While dicta may be persuasive or informative, they are not binding as precedent in the same way as the ratio decidendi.

Role in precedent: In common law systems, the ratio decidendi of a decision forms binding precedent for later cases with similar facts or issues. Courts identify the decidendi to determine the applicable rule of law. Non-binding observations within judgments (obiter dicta) may influence future reasoning but do not compel a particular outcome.

Variations and interpretation: Some judgments articulate a clear and single ratio decidendi, while others present multiple issues each with its own ratio. Dissenting or concurring opinions may propose alternative decidendi, which can influence subsequent developments in the law but are not binding unless adopted in later decisions.

See also: ratio decidendi, obiter dicta, stare decisis.