Res Judicata

Res Judicata is a principle or maxim in law that deals with cases already adjudicated and said cases, either quotes or the case itself is then used for substantiating the accuser or defendants proof of claim; expression of pre-existing rights, constitutional enforcement, the adherence to due process, or commanding the courts to act on a matter, make a decision or issue a judgment or decree in your favor, et alia.

Res judicata (RJ) 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 "issue 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 doctrine of res judicata is a method of preventing injustice to the parties of a case supposedly finished, but perhaps also or mostly a way of avoiding 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. Res judicata includes two related concepts: claim preclusion and issue preclusion (also called collateral estoppel or issue estoppel), though sometimes res judicata is used more narrowly to mean only claim preclusion.

Claim preclusion bars a suit from being brought again on an event which was the subject of a previous legal cause of action that has already been finally decided between the parties or those in privity with a party. Issue preclusion bars the re-litigation of issues of fact or law that have already been necessarily determined by a judge or jury as part of an earlier case. Res judicata is intended to strike a balance between competing interests. Its primary purpose is to assure an efficient judicial system. A related purpose is to create "repose" and finality.

Justice Stewart explained the need for this legal precept as follows:

Federal courts have traditionally adhered to the related doctrines of res judicata (claim preclusion) and collateral estoppel (issue preclusion). Under RJ, a final judgment on the merits of an action precludes the parties . . . from re-litigating issues that were or could have been raised in that action. Under collateral estoppel, once a court has decided an issue of fact or law necessary to its judgment, that decision may preclude re-litigation of the issue in a suit on a different cause of action involving a party to the first cause. As this court and other courts have often recognized, res judicata and collateral estoppel relieve parties of the costs and vexation of multiple lawsuits, conserve judicial resources, and by preventing inconsistent decisions, encourage reliance on adjudication.