Collateral Estoppel (Issue Preclusion)
What does "Collateral Estoppel (Issue Preclusion)" mean in law?
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.
Definition
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.
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.