Collateral Estoppel

Collateral estoppel has limited applicability in cases where the issues raised in the court where the action was first heard were beyond its jurisdiction. In antitrust cases brought in federal court, which has exclusive jurisdiction over such matters, prior state court rulings concerning antitrust violations made during the course of deciding the legality of a contract will not be given collateral estoppel effect. Courts reason that the punitive and exclusive nature of the federal remedy in antitrust cases precludes collateral estoppel based upon state court decisions.

In contrast, federal courts have applied collateral estoppel in patent cases to any underlying facts decided by state courts but not to facts alleged to prove the issue of patent validity or infringement.

The availability of collateral estoppel is also limited by changes in the law that take place between the original and subsequent action. Collateral estoppel will not apply if modifications in the applicable law alter the operative facts needed to obtain a favorable ruling. To do otherwise would deny an individual EQUAL PROTECTION of law merely because of the luck of the person who obtained the previous ruling.