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LawyerLand › Legal Glossary

Res Judicata and Collateral Estoppel (Preclusion)

The rules that stop a dispute from being litigated twice - claim preclusion, which bars a second suit on a claim that was or could have been decided, and issue preclusion, which bars re-arguing a specific issue actually decided, the elements of each, who is bound, the exceptions, and why "could have been raised" is the part that surprises people.

Informational only - this is not legal advice. These definitions explain general legal vocabulary in plain English. They are not advice about your situation, reading them creates no attorney-client relationship, and the law differs from state to state and changes over time. For advice you can rely on, speak to a lawyer licensed in your state.

What it means

Once a court has decided a dispute, the law treats that decision as final between the parties, and two related doctrines enforce that finality. Res judicata, now usually called claim preclusion, provides that a final judgment on the merits bars the same parties (and those in privity with them) from bringing a second suit on the same claim - and "the same claim" means the whole transaction or series of connected events, not merely the legal theories the first complaint happened to plead. A plaintiff who sued for breach of contract and lost cannot sue again for fraud on the same deal; a plaintiff who won damages for a car crash cannot return for the injuries that were left out. The doctrine bars claims that were actually decided and claims that could have been raised in the first action, which is the feature that catches people who split their case, hold something back, or sue in a court that could not hear all of it.

Collateral estoppel, or issue preclusion, is narrower and reaches further. It prevents a party from re-litigating a specific issue of fact or law that was actually litigated and necessarily decided in a prior case, even if the second case involves a different claim, provided the party against whom it is asserted had a full and fair opportunity to litigate the issue the first time. The requirements are strict: the issue must be identical, it must have been actually contested and decided rather than conceded or assumed, and the decision must have been essential to the judgment, not an aside. Modern law allows a stranger to the first case to use its result against a party who lost there - a plaintiff may rely on a finding made against the defendant in someone else's suit - but the reverse is never true: a person who was not a party to the first case, and had no chance to be heard, cannot be bound by it, because due process forbids it.

Both doctrines depend on a valid final judgment, and courts of one state and the federal courts must give the judgment of another the same preclusive effect it would have where it was rendered. A dismissal for lack of jurisdiction, improper venue or failure to join a party is not a judgment on the merits and precludes only the point decided; a voluntary dismissal without prejudice precludes nothing; a default judgment precludes the claim but, in most jurisdictions, no issue, since nothing was actually litigated. Settlements and consent judgments preclude what the parties agreed they would. A criminal conviction may be used to establish the underlying facts in a later civil suit by the victim, but an acquittal establishes nothing for civil purposes because of the different standard of proof. Preclusion is an affirmative defence that must be pleaded and is waived if it is not, and there are recognised exceptions - a change in the law, an intervening judgment, an issue of law in unrelated claims, a first forum whose procedures were too limited to be fair - that a court weighs before applying it.

Where this comes from

Claim and issue preclusion are common law, restated comprehensively in the Restatement (Second) of Judgments (1982): claim preclusion at §§ 17-26 (the transactional test at § 24), issue preclusion at §§ 27-29, the exceptions at §§ 26 and 28, and persons bound at §§ 34-63. Non-mutual offensive issue preclusion is Parklane Hosiery Co. v. Shore, 439 U.S. 322 (1979), and non-mutual defensive preclusion is Blonder-Tongue Laboratories, Inc. v. University of Illinois Foundation, 402 U.S. 313 (1971); the limits on binding non-parties are Taylor v. Sturgell, 553 U.S. 880 (2008). The obligation to honour another court's judgment is the Full Faith and Credit Clause and 28 U.S.C. § 1738, applied to state judgments in federal court by Allen v. McCurry, 449 U.S. 90 (1980), and Marrese v. American Academy of Orthopaedic Surgeons, 470 U.S. 373 (1985); the preclusive effect of federal judgments is Semtek International Inc. v. Lockheed Martin Corp., 531 U.S. 497 (2001). Preclusion as an affirmative defence is Federal Rule of Civil Procedure 8(c), and the effect of a dismissal is Rule 41(b). Each state's courts apply their own preclusion law to their own judgments, and the details - especially whether a default judgment supports issue preclusion - vary.

When people hire a lawyer for this

Preclusion is the reason a lawsuit has to be planned as a whole: every claim arising from the same events should be brought together, in a court that can hear all of them, or deliberately reserved with the court's leave, because what is left out is usually lost. A person who lost an earlier case - an administrative hearing, a small-claims trial, a family-court finding - should have a lawyer assess what that decision now prevents before filing anything new, and a defendant facing a second suit should raise the defence in the answer or lose it. The doctrines also cut the other way: a favourable finding in one case can be a powerful weapon in the next, and a lawyer who knows how to use it can shorten the second case considerably.

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Part of the LawyerLand plain-English legal glossary. Definitions are written from primary sources - statutes and court rules - and each entry states the authority it rests on, or says plainly when the doctrine is state law with no national rule.
If you cannot afford a lawyer, civil legal aid programmes provide free help with many of these problems: civil legal aid programmes by state.
Related free reference tools: statute of limitations for a personal-injury claim, by state, quoted from each state's official text - part of LawyerLand's legal reference tools.
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