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Ending Abuse of Patent Continuations

Mark A. Lemley

Stanford Law School

Kimberly A. Moore

affiliation not provided to SSRN


Boston University Law Review, Vol. 84, p. 63, 2004
UC Berkeley Public Law Research Paper No. 140
George Mason Law & Economics Research Paper No. 03-52

One of the oddest things to an outsider about the United States patent system is that due to continuation practice it is impossible for the U.S. Patent and Trademark Office (PTO) ever to finally reject a patent application. Continuation applications have led to abuse of the patent prosecution process. They serve very little useful purpose, and what benefits they confer may be outweighed by their potential for mischief. In an effort to study the pervasiveness of continuation practice, we compiled an original dataset comprising 2,224,379 patents, every patent issued from 1976 through 2000. We found that while continuations are filed in 23% of all patent applications, patents based on continuation applications represent 52% of all litigated patents. Although continuations are used in a minority of all patents, it is the most important minority because it is the minority most likely to end up in litigation. We examine the efforts undertaken to control the problems associated with continuation patents (changing the patent term, publishing applications, prosecution laches) and find them insufficient. The world would probably be a better place if they were abolished. Recognizing, however, that the abuse of continuation practice is not as pervasive as some might think, we propose a number of means by which Congress and the courts could strengthen existing rules designed to limit their abuse while preserving the practice. At a minimum, the empirical data we present can provide litigants and judges with a baseline for assessing the reasonableness of delay caused by the filing of multiple continuations by the patentee in determining the applicability of equitable remedies such as prosecution laches.

Number of Pages in PDF File: 61

Keywords: patent law, empirical studies, intellectual property

JEL Classification: K0, K2

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Date posted: October 28, 2003 ; Last revised: February 6, 2011

Suggested Citation

Lemley, Mark A. and Moore, Kimberly A., Ending Abuse of Patent Continuations (2003). Boston University Law Review, Vol. 84, p. 63, 2004; UC Berkeley Public Law Research Paper No. 140; George Mason Law & Economics Research Paper No. 03-52. Available at SSRN: http://ssrn.com/abstract=462404 or http://dx.doi.org/10.2139/ssrn.462404

Contact Information

Mark A. Lemley
Stanford Law School ( email )
559 Nathan Abbott Way
Stanford, CA 94305-8610
United States
Kimberly A. Moore (Contact Author)
affiliation not provided to SSRN
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