The Death of the Genus Claim

107 Pages Posted: 6 Aug 2020 Last revised: 19 Apr 2021

See all articles by Dmitry Karshtedt

Dmitry Karshtedt

George Washington University - Law School

Mark A. Lemley

Stanford Law School

Sean B. Seymore

University of Notre Dame - Notre Dame Law School

Date Written: August 5, 2020


The central feature of patent law in the chemical, biotechnology, and pharmaceutical industries is the genus claim – a patent that covers not just one specific chemical but a group of related chemicals. Genus claims are everywhere, and any patent lawyer will tell you they are critical to effective patent protection.

But as we show in this article, the law has changed dramatically in the last twenty-five years, to the point where it is no longer possible to have a valid genus claim. Courts almost always hold them invalid. Remarkably, they do this without having acknowledged that they have fundamentally changed an important area of law. More remarkably, patent lawyers and patent owners don’t seem to have noticed. Invention, investment, patenting, and patent litigation continue much as they had before. It’s just that the patents that are the basis of all that activity are invalid.

We document this surprising shift in the law. We explain why we think it represents both bad law and bad policy. We also explain why it hasn’t seemed to matter, and what that fact says about the relevance of law more generally in governing business behavior.

Keywords: patents, pharmaceuticals, intellectual property

Suggested Citation

Karshtedt, Dmitry and Lemley, Mark A. and Seymore, Sean B., The Death of the Genus Claim (August 5, 2020). Harvard Journal of Law & Technology, Forthcoming, GWU Legal Studies Research Paper No. 2021-06, GWU Law School Public Law Research Paper No. 2021-06, Available at SSRN: or

Dmitry Karshtedt

George Washington University - Law School ( email )

2000 H Street, N.W.
Washington, DC 20052
United States

Mark A. Lemley (Contact Author)

Stanford Law School ( email )

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

Sean B. Seymore

University of Notre Dame - Notre Dame Law School ( email )

Eck Hall of Law
Notre Dame, IN 46556
United States

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