Determinants of Patent Quality: Evidence from Inter Partes Review Proceedings

99 Pages Posted: 13 Feb 2018 Last revised: 3 Feb 2019

See all articles by Brian J. Love

Brian J. Love

Santa Clara University - School of Law

Shawn P. Miller

University of San Diego School of Law; Stanford Law School

Shawn Ambwani

Unified Patents, Inc.

Date Written: December 19, 2018


We study the determinants of patent “quality” — the likelihood that an issued patent can survive a post-grant validity challenge. We do so by taking advantage of two recent developments in the U.S. patent system. First, rather than relying on the relatively small and highly-selected set of patents scrutinized by courts, we study instead the larger and broader set of patents that have been subjected to inter partes review, a recently established administrative procedure for challenging the validity of issued patents. Second, in addition to characteristics observable on the face of challenged patents, we utilize datasets recently made available by the USPTO to gather detailed information about the prosecution and examination of studied patents. We find a significant relationship between validity and a number of characteristics of a patent and its owner, prosecutor, examiner, and prosecution history. For example, patents prosecuted by large law firms, pharmaceutical patents, and patents with more words per claim are significantly more likely to survive inter partes review. On the other hand, patents obtained by small entities, patents assigned to examiners with higher allowance rates, patents with more U.S. patent classes, and patents with higher reverse citation counts are less likely to survive review. Our results reveal a number of strategies that may help applicants, patent prosecutors, and USPTO management increase the quality of issued patents. Our findings also suggest that inter partes review is, as Congress intended, eliminating patents that appear to be of relatively low quality.

Keywords: patent quality, patent value, inter partes review, IPR, Patent Trial and Appeal Board, PTAB

JEL Classification: O34, K41

Suggested Citation

Love, Brian J. and Miller, Shawn Patrick and Ambwani, Shawn, Determinants of Patent Quality: Evidence from Inter Partes Review Proceedings (December 19, 2018). University of Colorado Law Review, Vol. 90, p. 67, 2019, Santa Clara Univ. Legal Studies Research Paper No. 2018-09, Available at SSRN: or

Brian J. Love (Contact Author)

Santa Clara University - School of Law ( email )

500 El Camino Real
Santa Clara, CA 95053
United States

Shawn Patrick Miller

University of San Diego School of Law ( email )

5998 Alcala Park
San Diego, CA 92110-2492
United States

HOME PAGE: http://

Stanford Law School ( email )

Stanford, CA 94305
United States

Shawn Ambwani

Unified Patents, Inc. ( email )

171 Main St. #106
Los Altos, CA 94022
United States

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