What are the Elements of Res Judicata (Claim Preclusion)?

Filing a lawsuit requires careful planning because a plaintiff might receive only one opportunity to assert their claims against a defendant in court. The doctrine of res judicata, also known as “claim preclusion,” prevents a party from re-litigating a claim once a court has issued a final judgment on that claim.

A closely related issue, “collateral estoppel” or “issue preclusion,” prevents someone from re-litigating a particular issue once a court has ruled on it. The term res judicata has, at times, been used to refer to both claim preclusion and issue preclusion. It is now more commonly associated with claim preclusion, and that is how we will use the term here. Since res judicata is almost entirely a product of common law, its elements and procedures may vary between state and federal courts, between courts in different states, and even between courts within a single jurisdiction. The following are the generally applicable elements of res judicata.

What Is Res Judicata?

The term res judicata is Latin for “a matter decided.” In a 2002 ruling, the California Supreme Court in Mycogen Corporation v. Monsanto Company stated that the doctrine of res judicata “prevents relitigation of the same cause of action in a second suit between the same parties or parties in privity with them.”

If a plaintiff successfully litigates a claim, resulting in a judgment in their favor, that plaintiff cannot assert the same claim against the same defendant in a later lawsuit. Similarly, if the litigation results in a final judgment for the defendant, the plaintiff cannot try again in a future lawsuit. That plaintiff’s options are limited to the available appellate procedures.

Elements of Res Judicata

The California Supreme Court’s definition of res judicata serves as a good overview of the concept. It identifies three general elements. Difficulties arise, of course, once one delves into the details of each element.

1. Relitigation

Under res judicata, a party cannot bring a claim in a lawsuit once that claim has been the subject of a final judgment in an earlier lawsuit. This usually applies to any new lawsuit filed in any court, not just the court that issued the earlier judgment.

This is perhaps the least complicated element of res judicata. Suppose, for example, that Person A files suit against Person B for false advertising under the Lanham Act in connection with a false statement to customers. A jury finds for Person B on all the claims. Person A cannot sue Person B for false advertising in connection with the same false statement again.

2. The Same Cause of Action

A party cannot bring the same claim, or cause of action, against the same defendant after a final judgment. We tend to use the terms “claim” and “cause of action” interchangeably, but they do not always have precisely the same meaning in a legal context.

In the Lanham Act example from earlier, suppose that the only cause of action in Person A’s original lawsuit was for false advertising. Res judicata, by itself, might not preclude Person A from suing Person B at a later time for other claims, such as antitrust violations arising out of the false statements. Since they already prevailed in a lawsuit for damages, however, collateral estoppel might prevent those new claims.

If a cause of action is for breach of contract, and Person A wins a verdict, they will likely be barred from filing another lawsuit arising from the same breach by Person B. If Person B allegedly breaches the same contract again, however, Person A will probably be free to file a new lawsuit.

3. The Same Parties, or Closely Related Parties

When the parties to a lawsuit are individuals, it is usually easy to determine when a new lawsuit involves the same parties. Res judicata can also bar lawsuits by a person or entity “in privity with” a party to the original lawsuit, as the California Supreme Court put it. This may include anyone acting as an agent for the original plaintiff, or a subsidiary of a corporate plaintiff. The same goes for defendants, such as when an unsuccessful plaintiff tries to bring the same claims against a subsidiary of the defendant or another closely related entity.

Exceptions to Res Judicata

Courts have identified several situations in which res judicata would not prevent a new lawsuit. They mostly address the manner in which a claim was dismissed, and they include:

  • Dismissal of a claim for lack of jurisdiction or improper venue;
  • Voluntary dismissal of a claim by a plaintiff;
  • Dismissal for want of prosecution;
  • Dismissal without prejudice, which often expressly states that a plaintiff may refile if they correct certain defects or errors in their pleadings; and
  • Failure to join a party under a mandatory joinder rule.

The jurisdiction issue can be particularly confusing when it involves lawsuits in both state and federal courts. A California appellate court addressed this challenge in a 2018 ruling. The plaintiff filed suit against an agency of the State of California in federal court, asserting claims under both federal and state laws. The U.S. District Court dismissed his state law claims for lack of subject matter jurisdiction under the Eleventh Amendment.

The plaintiff filed a new lawsuit in state court, asserting the same claims that the federal court had dismissed. The state appellate court held that res judicata did not preclude those claims, essentially because the dismissal in federal court was not based on the merits of the claims.