← The hardest concepts in United States law
In one breath
Claim preclusion (res judicata) bars a second lawsuit between the same parties over the same transaction, including claims that could have been brought the first time. Issue preclusion (collateral estoppel) stops a party from re-arguing a specific question that was actually decided, and had to be decided, in an earlier case, even if the second case is a different claim.
The picture
The final score and the referee’s ruling
A soccer game ends and the score is recorded. Nobody can come back next week and ask to replay that same game because they forgot to claim a goal. The result covers the whole game: every goal that could have been argued about that afternoon is settled with it. That is claim preclusion.
Now suppose that during the game a referee ruled, after a proper hearing from both captains, that a particular ball crossed the line. That ruling about one fact can follow the players into a later dispute, even a different one, such as a league inquiry about bonus payments, but only if the ruling was actually made, was needed to decide the game, and the player against whom it is used had a fair chance to argue the point. That is issue preclusion.
Where the picture stops working
The picture stops at who may use the ruling. A bystander in sport has no stake in the old game, but in law a stranger who was not a party can sometimes use an earlier ruling against a party who lost it. Federal courts allow this in their discretion (Parklane Hosiery), while states differ in how far they allow it.
How it really works
- 1Ask whether the first case ended in a valid final judgment on the merits, from a court with power to decide it. A dismissal for lack of jurisdiction, for example, generally does not bar the claim in a proper court.
- 2For claim preclusion, ask whether the parties (or those in privity with them) are the same and whether the second claim arises from the same transaction or series of transactions. Many courts follow the Restatement (Second) of Judgments, section 24, in drawing the line.
- 3If so, the claim is barred whether or not it was actually raised: claim preclusion covers everything that could have been brought on that transaction.
- 4For issue preclusion, ask four things: was the issue identical, was it actually litigated, was it necessary to the first judgment, and was the party to be bound a party, or in privity with one, who had a full and fair chance to litigate?
- 5Finally ask who is trying to use the earlier ruling. Who can invoke issue preclusion against whom varies by court and jurisdiction.
Why people get it wrong
- Mixing the two up. Claim preclusion works at the level of the whole lawsuit and its transaction, while issue preclusion works at the level of a single decided question.
- Thinking claim preclusion bars only what was actually argued. It also bars what could have been argued but was held back.
- Applying issue preclusion to an issue that was never decided, for example because the first case settled or the issue was only mentioned in passing.
- Applying it to an issue that was decided but unnecessary to the judgment. Such findings are usually not given preclusive effect.
- Forgetting the fair-chance requirement. A person who was never a party to the first case, and not in privity with a party, ordinarily cannot be bound by it.
A worked example
The facts are invented
A delivery van from Northgate Couriers hits Ravi’s car in an intersection. Ravi sues Northgate in the invented state of Fenn for the damage to his car. The jury finds the van driver ran the red light, and Ravi wins. Months later, Ravi also sues Northgate for his whiplash injury from the same collision.
The second suit fails on claim preclusion: both claims come from the same accident and could have been brought together, so the first judgment closed the whole transaction. Now change the second case. Suppose Ravi’s passenger, Ines, who was not a party to the first case, sues Northgate. Issue preclusion would not bind Northgate to the red-light finding automatically in every court, since Ines was not a party. In a federal court the judge may let her use it if that seems fair. Had Northgate been the plaintiff against Ravi in a later case, Ravi could be bound by that finding, because he had his chance to argue the point.
Try it
Marta sues her landlord for a broken heating system and loses at trial. A year later she sues the same landlord over a broken elevator from the same period of tenancy, a defect she knew about when she brought the first suit. What is the best analysis?
Landmark authorities
Read the sources themselves; this list is a starting point.
- Parklane Hosiery Co. v. Shore, 439 U.S. 322 (1979)
- Taylor v. Sturgell, 553 U.S. 880 (2008)
- Restatement (Second) of Judgments, sections 24 and 27
Where to go next
More hard concepts in United States law
- The Erie doctrine (Civil procedure)
- Personal jurisdiction and minimum contacts (Civil procedure)
- Standing, ripeness and mootness (Constitutional law)
This page is an educational overview. It is not legal advice and not a substitute for the sources: the statute, the rule, the case itself. United States law is made in fifty states and in the federal system, and the rules differ between them. Each page states the usual formulation of the rule and names landmark decisions; your own state, circuit or course may use different wording. Check the primary sources before relying on any rule.