Res judicata

Res judicata or res iudicata , also known as claim preclusion, is the Latin term for "a matter [already] judged", and refers to either of two concepts: in both civil law and common law legal systems, a case in which there has been a final judgment and is no longer subject to appeal; and the legal doctrine meant to bar (or preclude) continued litigation of a case on same issues between the same parties. In this latter usage, the term is synonymous with "preclusion".

In the case of res judicata, the matter cannot be raised again, either in the same court or in a different court. A court will use res judicata to deny reconsideration of a matter.

The legal concept of res judicata arose as a method of preventing injustice to the parties of a case supposedly finished, but perhaps mostly to avoid unnecessary waste of resources in the court system. Res judicata does not merely prevent future judgments from contradicting earlier ones, but also prevents litigants from multiplying judgments, and confusion.