The Doctrine of Equivalents and Claiming the Future after Festo

Federal Circuit Bar Journal, Fall 2004

39 Pages Posted: 6 Sep 2004


In two recent cases, Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997), and Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002), the Supreme Court unanimously approved of the modern doctrine of equivalents articulated in Graver Tank & Manufacturing Co. v. Linde Air Products Co., 339 U.S. 605 (1950). The Court also extended equivalents protection to later-arising technologies and imperfectly reconciled the modern doctrine with the doctrine of prosecution history estoppel for amended claims. The Court's new doctrine conflicts with historic implied-disclaimer standards. The U.S. Court of Appeals for the Federal Circuit has further revised the Supreme Court's reconciliation of these doctrines for amended claims, and has adopted different standards for claim construction and argument estoppel that conflict with the Court's new Festo standards. This article - forthcoming in the Federal Circuit Bar Journal - describes how the modern doctrine of equivalents operates and how it relates to prosecution history estoppel in light of the recent Supreme Court and Federal Circuit decisions. The article also discusses the differences between dedication of disclosed subject matter and implied disclaimer of equivalents and describes the conflicts that have been created among the claim scope, estoppel, and implied disclaimer doctrines. In particular, the article explains how the modern doctrine extends patent protection to later-arising equivalent technologies that the applicant could not have claimed and thus to which the modern doctrine should not apply.

This article is the first in a series of articles relating to the doctrine of equivalents. These articles seek to encourage and to set the context for future discussions of abolishing the modern doctrine of equivalents and of claiming later-arising technologies. The second article, to be published in two parts in the Journal of the Patent and Trademark Office Society, discusses the historic doctrine of equivalents, the Supreme Court's radical reshaping of the doctrine in Graver Tank, and historic limits on claiming later-arising technologies. The second article explains how the modern doctrine of equivalents conflicts with the requirement for distinct claims adopted in the 1870 Patent Act, was adopted by the Supreme Court without statutory support, and was neither codified nor impliedly ratified by Congress in the 1952 Patent Act. The third article, to be published in the Berkeley Technology Law Journal, discusses the lack of theoretical justification for the modern doctrine of equivalents, the social costs that it imposes, and the doctrinal complexity that it creates. The third article argues that the doctrine of equivalents should be restored to its historic form, limiting patent scope to the interpreted language of patent claims, and that the Supreme Court or Congress may need to impose additional limits on the ability to claim later-arising technologies in order to effectuate the Constitutional purpose of promoting progress.

Keywords: patents, doctrine of equivalents, claim scope, foreseeability, predictability, disclaimer, dedication, later-arising technology

JEL Classification: K39, K41, O31, O34

Suggested Citation

Sarnoff, Joshua D., The Doctrine of Equivalents and Claiming the Future after Festo. Federal Circuit Bar Journal, Fall 2004, Available at SSRN:

Joshua D. Sarnoff (Contact Author)

DePaul University College of Law ( email )

25 E. Jackson Blvd.
Chicago, IL Cook County 60604-2287
United States
312-362-6326 (Phone)

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