Is the Patent Office a Rubber Stamp?

28 Pages Posted: 9 Jul 2007 Last revised: 6 Feb 2011

See all articles by Mark A. Lemley

Mark A. Lemley

Stanford Law School

Bhaven N. Sampat

Columbia University - Mailman School of Public Health

Date Written: October 21, 2008


A growing chorus of voices is sounding a common refrain - the U.S. Patent and Trademark Office (PTO) is issuing far too many bad patents. These criticisms are complicated by the rather surprising fact that we don't actually know what percentage of patent applications actually issue as patents. In this paper, we use a novel dataset of all published patent applications filed in January 2001 to estimate the grant rate. These data also allow us to examine the uses of continuation applications, and to assess dynamics of applicant-examiner interaction over the patent prosecution process. We find that the PTO rejects a surprisingly high percentage of patents. While more than two-thirds of all applications result in at least one patent, a significant number of applications are rejected and then finally abandoned by the applicant. We also find that the likelihood of obtaining a patent varies significantly by industry, but in surprising ways. Finally, despite a variety of reforms that might be thought to reduce the use and abuse of continuation applications, we find a high use of continuation applications of various types.

Keywords: patent, patents, USPTO, intellectual property

JEL Classification: 034, K00

Suggested Citation

Lemley, Mark A. and Sampat, Bhaven N., Is the Patent Office a Rubber Stamp? (October 21, 2008). Emory Law Journal, Vol. 58, p. 181, 2008, Stanford Public Law Working Paper No. 999098, 2nd Annual Conference on Empirical Legal Studies Paper, Available at SSRN:

Mark A. Lemley

Stanford Law School ( email )

559 Nathan Abbott Way
Stanford, CA 94305-8610
United States

Bhaven N. Sampat (Contact Author)

Columbia University - Mailman School of Public Health ( email )

600 West 168th St. 6th Floor
New York, NY 10032
United States

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