Res Judicata

What is res judicata? Definition and purpose

Res judicata is Latin for "a matter judged." Once a court issues a final judgment, the dispute is over: the losing party can't simply file the same lawsuit again, and the winner can rely on the result. Korean civil law calls this effect 기판력, literally the "binding force of a judgment."

The reasons are practical. Without finality, a wealthy litigant could wear down an opponent by suing again and again; courts would waste time redeciding settled questions; and two courts could reach opposite answers on the same dispute. Finality is part of what due process promises: a fair hearing, and then an answer you can rely on.

The objective scope: what exactly is binding

Korean law limits res judicata to what is contained in the operative part of the judgment (주문), meaning the court's answer on the claim itself (Civil Procedure Act art. 216(1)). The reasons in the judgment, such as findings about facts or defenses, generally aren't binding in a later suit. If a court orders a buyer to pay the price of goods, the later court is bound on the existence of that price claim, but not necessarily on every fact the first court found along the way.

There is one notable exception. When a defendant raises set-off (상계) as a defense, the court's decision on whether the counterclaim exists is binding to the extent of the amount offset (art. 216(2)). Otherwise the same counterclaim could be used twice.

What counts as the "same claim"? Korean courts generally define the subject matter of a suit (소송물) by the specific right asserted, which makes claims narrower than in the U.S. American courts use a transactional test: under the Restatement (Second) of Judgments §24, claim preclusion bars every claim arising out of the same transaction or series of connected transactions, whether or not it was actually raised.

The subjective scope: who is bound

A judgment binds the parties, and also people who succeeded to the disputed right or obligation after the close of the hearing, and those who hold the disputed object on their behalf (art. 218(1)). If the losing defendant sells the disputed land after the hearing closed, the buyer can't escape the judgment. That's why a creditor can obtain a succession execution clause (승계집행문) to enforce the judgment against the successor under the Civil Execution Act art. 31.

When a person litigates on behalf of someone else, such as a trustee in bankruptcy, the judgment also binds the person whose right was asserted (art. 218(3)). Korea's Supreme Court applied this logic to the creditor's subrogation suit (채권자대위소송) in a 1975 en banc decision: when a creditor sues a third party in the debtor's place, the judgment binds the debtor if the debtor knew of the suit. Related questions about collection suits by multiple attaching creditors remain a favorite topic in civil procedure courses.

The question "who is bound?" sounds technical, but it's really about fairness. A judgment can't bind someone who never had a chance to be heard, unless their interests were truly represented.

The U.S. Supreme Court made the same point in Taylor v. Sturgell (2008), rejecting a broad theory of "virtual representation." Nonparties are bound only in limited situations, such as when they agreed to be bound, were adequately represented in a class action, or controlled the earlier litigation.

The temporal scope: the close of the hearing

A judgment speaks as of a particular moment. In Korea that moment is the close of the last hearing on the facts (사실심 변론종결 시). Facts that existed before that moment and could have been raised are cut off, even if a party didn't actually raise them. A defendant who loses a payment suit can't later argue that the debt had already been paid before the hearing closed.

Events after that point are different. If the debtor pays after the hearing closed, they can raise it in a suit objecting to enforcement (청구이의의 소). For periodic payments like future damages, a party can seek modification when circumstances change drastically (art. 252). The time cut keeps judgments final while leaving room for genuinely new facts.

Res judicata in the United States: claim and issue preclusion

American law divides res judicata into two branches. Claim preclusion bars relitigating the same claim, including claims that should have been brought in the first suit. Issue preclusion (collateral estoppel) prevents relitigating an issue of fact or law that was actually litigated, actually decided and essential to the judgment, even in a suit on a different claim.

Issue preclusion is where U.S. law goes furthest beyond Korea. In Parklane Hosiery Co. v. Shore (1979), the Supreme Court allowed "offensive nonmutual" issue preclusion: shareholders could rely on findings from an earlier SEC enforcement action the company had lost, so long as using those findings was fair. In Allen v. McCurry (1980), the Court held that federal courts must give state court judgments the preclusive effect the state would give them, reflecting the Full Faith and Credit statute.

Related effects and how they differ

Res judicata sits beside other effects of a judgment. Executory force (집행력) lets a winning party enforce the judgment through the civil procedure system's execution stage. Formative force (형성력) changes legal relationships directly, as in a divorce decree. The binding force on the court itself (기속력) prevents the issuing court from changing its own judgment after pronouncing it.

Students working through these doctrines can see them applied in Korean materials: Collection Suits and the Subjective Scope of Res Judicata in Korea: Comparison with Creditor Subrogation Suits compares how far the binding force of collection and subrogation suits reaches, and Succession Writs and Compulsory Auctions in Korea: When an Heir Enforces a Final Judgment, and the Subjective Scope of Enforceability shows how a judgment is enforced against a successor through a succession execution clause.

• Res judicata: the decided claim can't be relitigated.
• Executory force: the judgment can be enforced by compulsory execution.
• Formative force: the judgment itself creates or ends a legal relationship.
• Retrial (재심): the narrow door for reopening a final judgment with grave defects, such as forged evidence (art. 451).

A legal system that never lets go of a dispute can't deliver peace. Res judicata is the rule that tells everyone the argument is over, even when someone still thinks they were right.

What does res judicata mean in simple terms?

Once a court has finally decided a dispute, the same parties can't bring the same claim to court again.

What's the difference between res judicata and collateral estoppel?

In U.S. law, res judicata in the narrow sense bars the same claim, while collateral estoppel (issue preclusion) bars relitigating a specific issue that was actually decided.

Does a Korean judgment's reasoning have res judicata effect?

Generally no. Only the conclusion in the operative part binds, with set-off as the main exception.

Can a final judgment ever be reopened?

Yes, but only through narrow routes such as retrial for grave defects listed in the Civil Procedure Act.

References and official sources

1. 민사소송법. 국가법령정보센터
2. 민사집행법. 국가법령정보센터
3. Res judicata, Wex. Cornell LII
4. Collateral estoppel, Wex. Cornell LII
5. Parklane Hosiery Co. v. Shore, 439 U.S. 322 (1979). Justia
6. Taylor v. Sturgell, 553 U.S. 880 (2008). Justia