Inter Partes Review and the Design of Post-Grant Patent Reviews

38 Pages Posted: 3 May 2015 Last revised: 10 Feb 2019

See all articles by Colleen V. Chien

Colleen V. Chien

Berkeley Law School

Christian Helmers

Charles III University of Madrid; Santa Clara University - Leavey School of Business

Alfred Spigarelli

SGPS; Santarelli

Date Written: January 4, 2019


Inter partes review (IPR) is one of a number of mechanisms for eliminating improper patents through review of patents post-grant. While the purpose of IPRs is to provide a cheaper, more expert alternative to litigation for screening out bad patents, the devil is in the design details. For example, the inclusion of key procedural features in IPRs, such as fixed time frames and expanded discovery contributed to making it far more popular than its predecessors. As the United States weighs additional changes to the administration of IPRs, including expanding the basis for amendment and unifying standards of review, it is worth considering the experiences of the European Patent Office (EPO) and Germany with their parallel opposition and nullification (revocation) procedures. This Article compares and contrasts U.S. IPR, EPO opposition, and German revocation actions and explores what they suggest, collectively, about the optimal design of post-grant review systems.

Despite heightened concerns in the United States about IPR invalidation rates, outcomes are comparable across the three venues: 81% of reviewed claims and 26% of claims challenged in U.S. IPR proceedings are cancelled; 68% of patents reviewed and 63% of patents challenged in EPO opposition proceedings are amended or canceled; and 73% of the patents reviewed and 28% of the patents challenged in German revocation proceedings are partially or fully invalidated. But seemingly slight differences have contributed to the distinct roles each proceeding plays in its domestic patent system. The relative slowness of German infringement actions has translated into a parallel district action stay rate of 10–15%, as compared to an 80% stay rate among U.S. district court litigations that proceed in parallel to the IPR. Patentees also have fewer rights in U.S. IPRs than they do in EPO opposition proceedings, but have substantial rights to amend and can expect consolidated challenges. Focusing on how small differences have had big impacts on procedural and substantive outcomes, this Article discusses the implications of features such as the ability to amend and pre-institution decisions on the design and efficacy of post-grant patent reviews.

Keywords: patents, post-grant review, comparative studies

JEL Classification: O34, O48, O31

Suggested Citation

Chien, Colleen V. and Helmers, Christian and Helmers, Christian and Spigarelli, Alfred and Spigarelli, Alfred, Inter Partes Review and the Design of Post-Grant Patent Reviews (January 4, 2019). 33 Berk. TECH. LAW J. 817 (2019), Berkeley Technology Law Journal, Vol. 33, No. 817, 2019, Available at SSRN: or

Colleen V. Chien (Contact Author)

Berkeley Law School ( email )

302 JSP
2240 Piedmont Ave
Berkeley, CA 94720
United States
510-664-5254 (Phone)

Christian Helmers

Santa Clara University - Leavey School of Business ( email )

500 El Camino Real
Santa Clara, CA California 95053
United States

Charles III University of Madrid ( email )

CL. de Madrid 126
Madrid, Madrid 28903

Alfred Spigarelli

Santarelli ( email )

49, avenue des Champs-Elysées
Paris, 75008

SGPS ( email )

650 chemin des Vayoux
Auribeau sur Siagne, 06810

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