RES JUDICATA - Lat. "the thing has been decided" The principle that a final judgement of a competent court is conclusive upon the parties in any subsequent litigation involving the same cause of action.

The general rule is that a plaintiff who has prosecuted one action against a defendant and obtained a valid final judgment is barred by res judicata from prosecuting another action against the same defendant where (a) the claim in the second action is one which is based on the same factual transaction that was at issue in the first; (b) the plaintiff seeks a remedy additional or alternative to the one sought earlier; and (c) the claim is of such a nature as could have been joined in the first action. Underlying this standard is the need to strike a delicate balance between the interests of the defendant and of the courts in bringing litigation to a close and the interest of the plaintiff in the vindication of a just claim.

The Full Faith and Credit Act, 28 U.S.C. S 1738, requires that federal courts give a state-court judgment the same preclusive effect as would be given that judgment under the law of the State in which the judgment was rendered. Migra v. Warren City School Dist. Bd. of Educ., 465 U.S. 75, 81 (1984). Oregon courts adhere to standard principles of claim and issue preclusion. See Rennie v. Freeway Transp., 294 Or. 319 (1982).

The difference between the two concepts has been succinctly described by Justice Potter Stewart: The federal courts have traditionally adhered to the related doctrines of res judicata [claim preclusion] and collateral estoppel [issue preclusion]. Under res judicata, a final judgment on the merits of an action precludes the parties or their privies from relitigating 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 relitigation of the issue in a suit on a different cause of action involving a party to the first case. 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. Allen v. McCurry, 449 U.S. at 94. The collateral estoppel bar is inapplicable when the claimant did not have a full and fair opportunity to litigate the issue decided by the state court. Id. at 101. Thus, a claimant can file a federal suit to challenge the adequacy of state procedures.