Res judicata or res iudicata (RJ), also known as claim preclusion, is the Latin term for "a matter [already] judged", and may refer to 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 such cases between the same parties, which is different between the two legal systems. 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, so a prevailing plaintiff could not recover damages from the defendant twice for the same injury.
In common law 
The principle of res judicata may be used either by a judge or a defendant.
Once a final judgment has been handed down in a lawsuit, subsequent judges who are confronted with a suit that is identical to or substantially the same as the earlier one will apply the res judicata doctrine to preserve the effect of the first judgment.
A defendant in a lawsuit may use res judicata as defense. The general rule is that a plaintiff who prosecuted an action against a defendant and obtained a valid final judgment is not able to initiate another action versus the same defendant where:
- the claim is based on the same transaction that was at issue in the first action;
- the plaintiff seeks a different remedy, or further remedy, than was obtained in the first action;
- the claim is of such nature as could have been joined in the first action.
The Seventh Amendment to the United States Constitution provides that no fact having been tried by a jury shall be otherwise re-examinable in any court of the United States or of any state than according to the rules of law.
For res judicata to be binding, several factors must be met:
- identity in the thing at suit;
- identity of the cause at suit;
- identity of the parties to the action;
- identity in the designation of the parties involved;
- whether the judgment was final;
- whether the parties were given full and fair opportunity to be heard on the issue.
Regarding designation of the parties involved, a person may be involved in an action while filling a given office (e.g. as the agent of another), and may subsequently initiate the same action in a differing capacity (e.g. as his own agent). In that case res judicata would not be available as a defense unless the defendant could show that the differing designations were not legitimate and sufficient.
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.
It is often difficult to determine which, if either, of these concepts apply to later lawsuits that are seemingly related, because many causes of action can apply to the same factual situation and vice versa. The scope of an earlier judgment is probably the most difficult question that judges must resolve in applying res judicata. Sometimes merely part of the action will be affected. For example, a single claim may be struck from a complaint, or a single factual issue may be removed from reconsideration in the new trial.
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 a judication. REFER IN CASE OF Gerard Chuchumba v Rector of Itaga Seminary- this case give essential elements for application of plea of res judicata.
Exceptions to application 
Res judicata does not restrict the appeals process, which is considered a linear extension of the same lawsuit as the suit travels up (and back down) the appellate court ladder. Appeals are considered the appropriate manner by which to challenge a judgment rather than trying to start a new trial. Once the appeals process is exhausted or waived, res judicata will apply even to a judgment that is contrary to law. In states that permit a judgment to be renewed, a lawsuit to renew the judgment would not be barred by res judicata, however in states that do not permit renewal by action (as opposed to renewal by scire facias or by motion), such an action would be rejected by the courts as vexatious.
There are limited exceptions to res judicata that allow a party to attack the validity of the original judgment, even outside of appeals. These exceptions—usually called collateral attacks—are typically based on procedural or jurisdictional issues, based not on the wisdom of the earlier court's decision but its authority or on the competence of the earlier court to issue that decision. A collateral attack is more likely to be available (and to succeed) in judicial systems with multiple jurisdictions, such as under federal governments, or when a domestic court is asked to enforce or recognize the judgment of a foreign court.
In addition, in matters involving due process, cases that appear to be res judicata may be re-litigated. An example would be the establishment of a right to counsel. People who have had liberty taken away (i.e., imprisoned) may be allowed to be re-tried with a counselor as a matter of fairness.
RJ may not apply in cases involving the England reservation. If a litigant files suit in federal court, and that court stays proceedings to allow a state court to consider the questions of state law, the litigant may inform the state court that he reserves any federal-law issues in the action for federal court. If he makes such a reservation, RJ would not bar him from returning the case to federal court at conclusion of action in state court.
RJ may be avoided if claimant was not afforded a full and fair opportunity to litigate the issue decided by a state court. He could file suit in a federal court to challenge the adequacy of the state's procedures. In that case the federal suit would be against the state and not against the defendant in the first suit.
RJ may not apply if consent (or tacit agreement) is justification for splitting a claim. If plaintiff splits a claim in the course of a suit for special or justifiable reasons for doing so, a judgment in that action may not have the usual consequence of extinguishing the entire claim.
Failure to apply 
When a subsequent court fails to apply res judicata and renders a contradictory verdict on the same claim or issue, if a third court is faced with the same case, it will likely apply a "last in time" rule, giving effect only to the later judgment, even though the result came out differently the second time. This situation is not unheard of, as it is typically the responsibility of the parties to the suit to bring the earlier case to the judge's attention, and the judge must decide how broadly to apply it, or whether to recognize it in the first place. See Americana Fabrics, Inc. v. L & L Textiles, Inc., 754 F.2d 1524, 1529-30 (9th Cir. 1985).
In civil law 
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The doctrine of res judicata in nations that have a civil law legal system is much narrower in scope than in common law nations.
In order for a second suit to be dismissed on a motion of res judicata in a civilian jurisdiction, the trial must be identical to the first trial in the following manner: (1) identical parties, (2) identical theories of recovery, and (3) identical demands in both trials. In other words, the issue preclusion or collateral estoppel found in the common law doctrine of res judicata is not present in the civilian doctrine. In addition if all else is equal between the two cases, minus the relief sought, there will be no dismissal based on res judicata in a civil law jurisdiction.
While most civilian jurisdictions have slightly broadened the doctrine through multiple exceptions to these three requirements, there is no consensus on which exceptions ought to be allowed.
A very common use of the res judicata principle is to preclude plaintiffs after a class action suit has been settle even on plaintiffs who were not part of the original action because they could have joined that original action. 
Note: Louisiana (USA), a civil law jurisdiction, has in the last twenty years begun to follow the common law doctrine of res judicata.
In international law 
Arguably, res judicata is a general principle of international law under Article 38 (1)(c) of the International Court of Justice Statute. "The Court, whose function is to decide in accordance with international law such disputes as are submitted to it, shall apply: ... c. the general principles of law recognized by civilized nations".[clarification needed]
Similar provisions are also found in the International Covenants on Civil and Political Rights, and Article 4 of Protocol 7 of the European Convention on Human Rights. However, in the two said conventions, the application of res judicata is restricted to criminal proceedings only. In the European Convention, reopening of a concluded criminal proceedings is possible if -
(a) it is in accordance with the law and penal procedure of the State concerned; (b) there is evidence of new or newly discovered facts, or (c) if there has been a fundamental defect in the previous proceedings,
which could affect the outcome of the case.
In other uses 
The term is also sometimes used in related contexts. During the release of the SCOTUS judgement on the Affordable Care Act, the writers of SCOTUSBlog described how their interpretation of the judgement (that the law had been upheld) was challenged by their readers solely on the basis that other news networks had made the (erroneous) call earlier than them, thus giving their interpretation a veneer of respectability on the basis of having been the first.
See also 
- 11 U.S.C. sec. 1141(a)
- Allen v. McCurry, 449 U.S. 90, 94, 101 S.Ct. 411 (1980).
- England v. Louisiana State Board of Medical Examiners, 375 U.S. 411 (1964)
- Statute of the International Court of Justice: Chapter II Article 38.1.c
- "Beck's Law Dictionary": A Compendium of International Law Terms and Phrases on the website of the University of Virginia