---
title: "Collateral Estoppel (Issue Preclusion)"
type: Legal Term
source: https://casebriefly.com/legal-terms/collateral-estoppel
---

# Collateral Estoppel (Issue Preclusion)

Collateral estoppel, or issue preclusion, prevents the relitigation of specific factual or legal issues that were actually litigated and necessarily decided in a prior proceeding. Unlike res judicata, which bars entire claims, collateral estoppel applies to discrete issues. Traditionally, mutuality of parties was required, but the modern trend allows non-mutual offensive and defensive use of collateral estoppel, subject to fairness considerations.

## Related Terms

- res-judicata
- full-faith-and-credit
- summary-judgment

## Related Cases

- parklane-hosiery-v-shore
- blonder-tongue-v-university-of-illinois-foundation
- cromwell-v-county-of-sac

## Example

A court finds that a defendant ran a red light. In a subsequent suit by a different plaintiff, the defendant is collaterally estopped from relitigating whether they ran the red light.

---
Source: [Collateral Estoppel (Issue Preclusion) — CaseBriefly](https://casebriefly.com/legal-terms/collateral-estoppel)