The Death of the Genus Claim

72 Pages Posted: 6 Aug 2020 Last revised: 11 Feb 2022

See all articles by Dmitry Karshtedt

Dmitry Karshtedt

George Washington University - Law School

Mark A. Lemley

Stanford Law School

Sean B. Seymore

Vanderbilt University - 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 claim 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 thirty years, to the point where it is nearly impossible to maintain a valid genus claim. Courts almost always hold them invalid, either at trial or on appeal. Remarkably, courts do this without acknowledging that they’ve fundamentally changed an important area of law. More remarkably, it’s not clear that patent lawyers and patent owners have noticed this shift. Invention, investment, patenting, and patent litigation continue much as they have before, but the genus patents that are thought to be the basis of this activity generally end up invalid.

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

Keywords: patents, pharmaceuticals, intellectual property

JEL Classification: O31, O32, O33, O34, O38, O40

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, Vol. 35, 2021, pp. 1-72, GWU Legal Studies Research Paper No. 2021-06, GWU Law School Public Law Research Paper No. 2021-06, Vanderbilt Law Research Paper No. 21-14, 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

Vanderbilt University - Law School ( email )

131 21st Avenue South
Nashville, TN 37203-1181
United States

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