Foreseeability as a Bar to the Doctrine of Equivalents

Abstract

Several opinions in these cases suggest that a patentee should not be able to invoke the doctrine of equivalents to obtain protection from equivalents that one skilled in the art would have reasonably foreseen before the patent issued. Federal Circuit Judge Rader, in particular, is a strong advocate of such a "foreseeability bar." The United States and the Institute of Electrical and Electronics Engineers (IEEE) also advanced the idea in their amici briefs to the Supreme Court in Festo Corp. v. Shoketsu Kinzoku Kogyu Kabushiki Co., the Court's latest case involving the issue. The Court's opinion in that case also appears to limit the doctrine's reach in cases involving amended claims to cover only those complained-of equivalents that were not foreseeable when the patentee amended its claims. This paper examines a series of cases related to the applicability of foreseeability to the doctrine of equivalents. It then attempts to synthesize the current state of the law in the area, and analyzes arguments for and against adopting a foreseeability rule.