A matter already settled in court; cannot be raised again WordNet 3.0 & Open English WordNet

Res judicata or res iudicata, also known as claim preclusion, is the Latin term for matter decided 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 that is no longer subject to appeal; and the legal doctrine meant to bar relitigation of a claim between the same parties. Wikipedia

Claim preclusion in law Wikidata

An issue that has already been decided by another court, and therefore must be dismissed. Wiktionary

Rule. Wiktionary (translation)