Res Judicata

The doctrine that a matter finally decided by a competent court cannot be litigated again

Overview

Latin for a matter judged, res judicata holds that once a court has reached a final judgment on the merits, the same parties may not bring the same claim again. Modern common law divides it into claim preclusion, which bars relitigating a claim that was or could have been raised, and issue preclusion, sometimes called collateral estoppel, which prevents a party from relitigating a specific issue already decided against it. Rooted in Roman law and recognized in civil law systems too, the doctrine protects the finality of judgments, saves judicial resources, and spares defendants repeated suits. The double jeopardy rule serves a similar purpose in criminal law.