The Doctrine of Equivalents Isn’t Very Important

Of every 100 findings of direct infringement by U.S. courts, only about 10 are findings of direct infringement under the doctrine of equivalents.1

This number sheds light on the importance of DOE claim scope relative to literal claim scope. Some applicants may spend a lot of time and energy on the DOE and the nuances of the Festo case and its progeny, or go to lengths to avoid amending claims in ways that could curb DOE protection. When that translates into giving short shrift to the literal language of claims, it’s the tail wagging the dog. Applicants should bear in mind that when a patent is found infringed, nine out of ten times it’s found literally infringed.


  1. This 10% figure is based on a dataset consisting of 3316 case decisions from 2005 to 2013, which were coded as to rulings on 40 legal issues by the University of Houston Law Center. The dataset includes all Federal Circuit rulings (including summary affirmances under Rule 36) and all reported lower rulings from district courts and the ITC. See U.S. Patent Litigation Statistics, Institute for Intellectual Property and Information Law, University of Houston Law Center, at (visited Jan. 2017). See also John R. Allison & Mark A. Lemley,The (Unnoticed) Demise of the Doctrine of Equivalents, 59 Stanford L. Rev. 955 (April 2010); Lee Petherbridge, On the Decline of the Doctrine of Equivalents, 31 Cardozo L. Rev. 1371 (2010).
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