30 Pages Posted: 27 Oct 2012 Last revised: 25 Feb 2013

See all articles by Lee Petherbridge

Lee Petherbridge

Loyola Law School Los Angeles

Jason Rantanen

University of Iowa - College of Law

R. Polk Wagner

University of Pennsylvania Law School

Date Written: February 22, 2012


The patent doctrine of inequitable conduct — which allows a patent to be held unenforceable on the basis of misbehavior by the applicant during patent prosecution — has been the subject of intense criticism from the bench and bar alike. And yet to date there has been no systematic attempt to determine whether the doctrine is or is not working as theorized. This study fills that gap. We evaluate the performance of the inequitable conduct doctrine with a novel methodological approach: by empirically characterizing the differences between patents found unenforceable and several other types of patents (unlitigated, litigated, invalid, obvious, and under-disclosed), we use those differences to reveal the real-world impact of the inequitable conduct doctrine. We find that patents held unenforceable have clear hallmarks of risky prosecution behavior, such as longer pendency and fewer disclosures of prior art as compared to all other types we studied. These results indicate that the doctrine is likely to be operating better than the conventional wisdom would suggest.

Keywords: patents, unenforceability, inequitable conduct, empirical, patent data

Suggested Citation

Petherbridge, Lee and Rantanen, Jason and Wagner, R. Polk, Unenforceability (February 22, 2012). U of Penn Law School, Public Law Research Paper No. 12-28, U of Penn, Inst for Law & Econ Research Paper No. 12-15, U Iowa Legal Studies Research Paper No. 12-10, Loyola-LA Legal Studies Paper No. 2012-28, 7th Annual Conference on Empirical Legal Studies, Available at SSRN: https://ssrn.com/abstract=2167417 or http://dx.doi.org/10.2139/ssrn.2167417

Lee Petherbridge

Loyola Law School Los Angeles ( email )

919 Albany Street
Los Angeles, CA 90015-1211
United States
213-736-8194 (Phone)
213-380-3769 (Fax)

Jason Rantanen

University of Iowa - College of Law ( email )

Melrose and Byington
Iowa City, IA 52242
United States

R. Polk Wagner (Contact Author)

University of Pennsylvania Law School ( email )

3501 Sansom Street
Philadelphia, PA 19104
United States
267-433-4431 (Phone)

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