The Doctrine of Equivalents in Various Patent Regimes: Does Anybody Have It Right?
49 Pages Posted: 27 Feb 2013
Date Written: 2009
This article focuses on the scope of a patent’s protection and compares the rules in the United States, United Kingdom, Germany, and Japan. In the United States, the Supreme Court case Winans v. Denmead, which held that a patent is infringed by something that achieves the same result by using a different form, is the starting point for the doctrine of equivalents. In Graver Tank & Manufacturing Co. v. Linde Air Products Co., the Supreme Court later described the doctrine of equivalents as prohibiting “fraud on the patent.” In Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., the Court adopted a test based on whether the patent writer would have foreseen an infringement. In contrast, English law approaches the issue from a “purposive construction” angle, which requires that a “variant or equivalent must fall within the language of a claim.” The article also discusses the European Patent Convention, with which the United Kingdom complies. Third, Germany approaches the doctrine of equivalents by asking four questions: 1) whether the second item has “the same technical effect,” 2) whether the creator of the second item knew that it would have “the same effect,” 3) whether the creator the second item knew about “the technical teaching of the patent claim,” and 4) whether the second item is “anticipated or made obvious by the state of the art.” Finally, in Japan, the doctrine of equivalents received judicial recognition in 1998 and focuses on the “essential part” of a creation; however, lower courts seem to rely on an “all elements rule,” which leads to inconsistent application of the doctrine of equivalents.
Keywords: patents, doctrine of equivalents, scope
JEL Classification: O31, O34, O57
Suggested Citation: Suggested Citation