Legal Dictionary

collateral estoppel

Definition of collateral estoppel


collateral estoppel (uncountable)

  1. The estoppel forbidding again litigating an issue decided in a previous case with the same parties, or even with the same party being estopped.

Further reading

Collateral estoppel (CE), known in modern terminology as issue preclusion, is a common law estoppel doctrine that prevents a person from relitigating an issue. One summary is that "once a court has decided an issue of fact or law necessary to its judgment, that decision ... preclude[s] relitigation of the issue in a suit on a different cause of action involving a party to the first case."[1] The rationale behind issue preclusion is the prevention of legal harassment and the prevention of abuse of legal resources.


Parties may be estopped from litigating determinations on issues made in prior actions. The determination may be an issue of fact or an issue of law. Preclusion requires that the issue decided was actually and necessarily decided as part of a valid final judgment. Valid final judgments of state courts are given preclusive effect in other state and federal courts under the Full Faith and Credit Clause of the U.S. Constitution.

Valid final judgments must be issued by courts with appropriate personal and subject matter jurisdiction. It is notable, however, that an error does not make a decision invalid. Reversible errors must be appealed. The legal defense (CE) applies even if an erroneous judgment, or erroneous use of legal principles, occurred in the first action. An incorrect conclusion of the court in the first suit does not cause defendant to forsake the protection of res judicata (and by extension, of CE)[2] A judgment need not be correct to preclude further litigation; it is sufficient that it be final, and that it have been decided on the merits of the case.

Collateral estoppel does not prevent an appeal of a decision, or a party from asking the judge for re-argument or a revised decision. In federal court, judgments on appeal are given preclusive effect. However, if the decision is vacated, the preclusive effect of the judgment fails.


  1. San Remo Hotel v. San Francisco, 545 U.S. 323 (2005), fn. 16.
  2. Federated Dept. Stores v. Moitie, 452 U.S. 394 (1981)


  1. Wiktionary. Published under the Creative Commons Attribution/Share-Alike License.


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