Ruth Mason

Ruth Mason’a scholarship examines tax law, with particular focus on international tax, tax discrimination in the United States and European Union, EU state aid and fiscal federalism.

Working with Michael Knoll over the last two decades, Mason has developed an influential account of tax discrimination grounded in comparative advantage and federalism. In Comptroller of Maryland v. Wynne, the U.S. Supreme Court adopted that approach, citing Mason’s scholarship and an amicus brief written by Knoll and Mason.

A Max Planck Law Fellow, Mason has received multiyear funding to study federalism and fiscal solidarity, work that supports her current books on tax discrimination and EU state aid. Rethinking Tax Competition, with Michael Knoll, is forthcoming from Harvard University Press, and Tax State Aid After Apple, with Stephen Daly, is under contract with Oxford University Press. With Tsilly Dagan, she also co-edited Taxing People: The Next 100 Years, published by Cambridge University Press.

Mason has lectured widely in the United States and abroad. She delivered the 2025 Tillinghast Lecture and has presented her work in many countries. She has been a visiting professor at Yale Law School and the University of Paris Panthéon-Sorbonne, a Fulbright Senior Scholar at Vienna University of Economics and Business, and a Visiting Global Scholar at the International Bureau of Fiscal Documentation. Mason is a member of the American Law Institute and the American College of Tax Counsel.

At UVA, Mason co-founded the Oxford-Virginia Legal Dialogs. She teaches taxation, supervises doctoral students, and advises UVA Law’s international tax moot court team, which has won four international championships.

Mason received her undergraduate degree in U.S. history from Columbia University and her law degree from Harvard Law School.