Home > West's Encyclopedia of American Law > Collateral Estoppel

A doctrine by which an earlier decision rendered by a court in a lawsuit between parties is conclusive as to the issues or controverted points so that they cannot be relitigated in subsequent proceedings involving the same parties.

Collateral estoppel is an AFFIRMATIVE DEFENSE that must be pleaded by a defendant in civil actions. The similar affirmative defense of RES JUDICATA differs from collateral ESTOPPEL in that it completely precludes the relitigation of a claim, demand, or CAUSE OF ACTION, as opposed to an issue or controverted point, in a subsequent proceeding between the same parties to an earlier action.

The application of the...