Abstract

     Since the Supreme Court’s decision in Markman, courts have struggled to determine whether one court’s claim interpretation is binding on another court, and the decisions have not been uniform. Some courts have held that claim interpretation has a special finality and collateral estoppel always applies to an earlier claim interpretation, and others have held it does not. As scholars debated the issue, the Federal Circuit appeared content to remain silent. In  the case of RF Delaware, Inc. v. Pacific Keystone Technologies, Inc., however, the Federal Circuit finally considered the issue.
     In RF Delaware, the Federal Circuit held that collateral estoppel did not apply to the earlier claim constructions because the required standard for finality was not met. The court held that the lower court’s orders granting partial summary judgment and the following settlement were not sufficiently firm to have preclusive effect. With its decision, the Federal Circuit clarified some of the questions that the lower court decisions were unable to answer, although the RF Delaware court never acknowledged either the growing circuit split or its clarification of that split.
     Part I of the Article provides an overview of patent law, claim interpretation, collateral estoppel, and examines pre- and post- Markman decisions on collateral estoppel, focusing especially on the “essential to final judgment” element. Part II examines the Federal Circuit’s decision in  RF Delaware. Part III analyzes the Federal Circuit’s decision and suggests how the decision affects the law of collateral estoppel of claim interpretation. This Article concludes that collateral estoppel can apply to a court’s claim interpretation, but there is no special finality to a claim interpretation, and the form of the court’s Markman hearing may affect whether collateral estoppel can apply to the claim interpretation.