The Historic and Modern Doctrines of Equivalents and Claiming the Future: Part II (1870-1952)

Document Type


Publication Date

January 2004


This article is the second 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 first article, to be published in the Federal Circuit Bar Journal, describes conflicts among the modern doctrine and prosecution history estoppel and additional implied disclaimer and claim scope doctrines. It explains how the modern doctrine improperly extends patent protection to equivalents that could not validly be claimed. The third article, to be published in the Berkeley Technology Law Journal discusses the lack of theoretical justification for, social costs of, and complexity created by the modern doctrine. It argues that the historic doctrine of equivalents should be restored and that additional limits on claiming later-arising technologies may be needed to promote progress.