Although there are few restriction on the use of courts to litigate claims, the courts impose basic rules to prevent the relitigation of claims, including the harassment of a party through repeated lawsuits over the same subject matter, and also to improve judicial economy by preventing the litigation of claims that reasonably should have been decided within the course of a prior lawsuit. Those rules are:
- Issue Preclusion: Also known as collateral estoppel, prevents a party from relitigating a claim that the party has already litigated
- Claim Preclusion: Also known as res judicata, a latin phrase meaning "a matter judged", issue preclusion applies to prevent a party to a lawsuit from litigating a claim more than once.
These defenses to litigation apply to the parties involved in the litigation, and also to their privies. Parties are privies (in privity with each) other when they have a relationship that is recognized by law, such as a relationship based upon contract, shared ownership of real estate, or other lawful relationship.
The application of claim and issue preclusion are similar in U.S. jurisdictions, but differences in state law and procedure may affect their application to a specific case or type of case.
Issue preclusion arises when a question of fact has been litigated, and a judgment on the merits has been reached. Issue preclusion does not apply to conclusions of law.
Following a judgment on the merits, the issue may not be relitigated by a party bound by the decision or that party's privies. In simpler terms, issue preclusion prevents a party from litigating the same issue more than once.
Issue preclusion must normally be raised as an affirmative defense, with the defendant raising the claim required to prove:
- There was prior litigation in which the identical issue was brought before the court;
- The issue was actually litigated in that prior legal proceeding, and the party against which issue preclusion is being asserted had a full and fair opportunity to litigate the issue in the that proceeding.
- The issue was decided as a necessary part of the court’s final judgment in the prior litigation.
A party does not need to have been involved in the prior litigation in order to raise the defense of issue preclusion, but it can only be raised against a party to the prior litigation.
- In non-mutual, defensive collateral estoppel, a defendant seeks to prevent a plaintiff from relitigating a claim that the plaintiff was not successful in litigating against another defendant.
- In non-mutual, offensive collateral estoppel, a plaintiff seeks to prevent a defendant from relitigating a claim that the defendant was not successful in litigating against another plaintiff. This defense is more difficult to assert, and may require that the plaintiff demonstrate that it could not have joined the prior litigation, or that the result of issue preclusion would not be unfair to the defendant.
Issue preclusion does not stop parties from suing each other over issues not raised in the prior litigation, but those claims may be bared by the related doctrine of claim preclusion (res judicata).
Narrow exceptions may arise to collateral estoppel, such that the prior litigation does not bar the relitigation of an issue in a subsequent lawsuit. For example,
- If the law changes after the initial determination, and the changes may have affected the outcome of the litigation such that a party might have received a more favorable outcome, it will likely be possible for that party to again litigate the issue despite the prior judgment.
- A party to a prior case may attempt to convince the court that the party was not afforded a full and fair opportunity to defend against the prior claim, and thus should not be bound by the outcome of the prior case.
- If the prior litigation occurred in another jurisdiction, in order to assert issue preclusion the plaintiff may have to demonstrate that differences in law between the jurisdictions would not have affected the outcome of the prior case.
In most cases, issue preclusion is asserted in one civil lawsuit based upon the outcome of a prior civil lawsuit. However, collateral estoppel may at times apply in a civil lawsuit based upon the outcome of another type of case, such as a criminal case or a workers' compensation case. For example:
- If a criminal defendant is convicted of a crime, that defendant may be precluded from claiming innocence in a later civil proceeding. However the outcome of a civil proceeding would not bind a criminal court as criminal cases are determined under a higher burden of proof.
- A person injured on the job who files a workers' compensation claim and a personal injury claim (for example, a product liability claim alleging defective equipment) who is later determined in the workers' compensation case not to have been injured at work may be bound by that determination in the personal injury case.
Claim preclusion applies when the parties to a lawsuit have previously litigated the same claim, and have previously obtained a final judgment on the merits of that claim. Only the parties to the prior lawsuit can raise the defense of claim preclusion.
Claim preclusion falls into two categories:
- Bar: A plaintiff who lost a prior lawsuit cannot again sue the victorious defendant on the same cause of action.
- Merger: A plaintiff who won a prior lawsuit cannot again sue the losing defendant on the same cause of action.
To seek the dismissal of a claim on the basis of collateral estoppel, the defendant must demonstrate:
- The claim in the current legal action is based upon the same set of facts that were at issue in the prior legal action;
- The parties to the current legal action are the same as the parties in the prior legal action, or are in privity with the parties in the first action in relation to the claim at issue;
- The plaintiff in the current legal action is seeking a remedy that is in addition to or in alternative to the remedy sought in the prior action; and
- The plaintiff's claim is of such a nature that it could have been made during the prior legal action.
To put it another way, claim preclusion bars a party from bringing a claim if a court of competent jurisdiction has rendered final judgment on the merits in a previous action involving the same parties and claims. Although historically claim preclusion applied only based upon a verdict after trial, the modern approach applies claim preclusion to cases that were decided through summary proceedings based upon the plaintiff's failure to state a valid claim.
Claim preclusion applies even if the second claim is based upon a different theory or cause of action. For example, claim preclusion would bar an attempt by the plaintiff to sue a defendant for fraud after a prior lawsuit for breach of contract arising from the same acts by the defendant. Similarly, if a plaintiff is injured in a car accident and suffers both a broken arm and a broken leg, but sues the defendant only for damages relating to the broken leg, the plaintiff will not be permitted to sue the same defendant a second time to recover damages for the broken arm.
When a case is decided for reasons other than its merits, claim preclusion does not apply. For example, claim preclusion does not apply when a court dismisses a case because it lacks jurisdiction over the parties or subject matter, or because the case was filed in an improper venue. It does not apply to the dismissal of a case that occurs without prejudice (a type of dismissal that allows a claim to potentially be refiled).
Narrow exceptions exist to the broad rule of claim preclusion. For example:
- A lawsuit might involve both state and federal legal issues, with the parties agreeing to separately litigate state law claims in state court and federal law claims in federal court.
- A federal court may stay proceedings in order to allow for the parties to litigate specific issues in state court, with the federal issues reserved for later determination in federal court once the state court issues are resolved.
- Some states exclude from claim preclusion the determination of issues through declaratory judgments. A declaratory judgment is a type of judgment that determines the rights of the parties without ordering any remedy or awarding damages.
The key differences between claim preclusion and issue preclusion are as follows:
- The Same Issues: For issue preclusion (collateral estoppel) to apply, the issues in the first and second cases must be identical or nearly identical. For claim preclusion (res judicata) the same legal issue must be involved in both cases, but the subject matter of the litigation may be different.
- Litigation on the Merits: For issue preclusion to bar a claim, the claim must have been previously litigated on its merits. Claim preclusion may apply even if the issue was not previously litigated.
- Final Judgment: For both defenses, a final judgment must have been reached on the merits of the prior case. However, even if the issue was raised in previous litigation, issue preclusion cannot apply to a later lawsuit where the issue has no connection to the judgment or was not decided as part of the judgment. Claim preclusion may apply even though the issue was not part of the judgment.