Prior Art in Inter Partes Review

30 Pages Posted: 25 Jun 2019 Last revised: 30 Aug 2019

Date Written: June 24, 2019


This Essay is an empirical study of the evidence the Patent Trial and Appeal Board relies upon when cancelling patents in inter partes review. To construct our dataset, we collected every final written decision invalidating a patent claim over a twelve-month period. We coded individual invalidation events on a reference-by-reference, claim-by-claim basis. Drawing on this dataset, we report a number of details about the prior art supporting patent cancellation, including the frequency with which U.S. patents, foreign patents, and printed publications were cited, the frequency with which the invalidating prior art would have been amenable to a pre-filing prior art search, and whether the invalidating prior art was known at the time of examination.

Keywords: patent law, prior art, USPTO, PTAB

JEL Classification: K23, K41, O30, O31, O32, O33, O34, O38

Suggested Citation

Yelderman, Stephen, Prior Art in Inter Partes Review (June 24, 2019). 104 Iowa Law Review 2705 (2019), Notre Dame Legal Studies Paper No. 1940, Available at SSRN:

Stephen Yelderman (Contact Author)

Notre Dame Law School ( email )

P.O. Box 780
Notre Dame, IN 46556-0780
United States

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