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Last Term, a sharply divided Supreme Court decided a landmark dormant Commerce Clause case, Comptroller of the Treasury of Maryland v. Wynne. Wynne represents the Court’s first clear acknowledgement of the economic underpinnings of one of its main doctrinal tools for resolving tax discrimination cases, the internal consistency test. In deciding Wynne, the Court relied on economic analysis we provided. This Essay explains that analysis, why the majority accepted it, why the dissenters’ objections to the majority’s reasoning miss their mark, and what Wynne means for state taxation. Essential to our analysis and the Court’s decision in Wynne is the idea that states are capable of discriminating not only on an inbound basis, but also on an outbound basis, and that the Commerce Clause prohibits discrimination on either basis. To aid in explicating our position, this Essay introduces the term “retentionism” as an analogue to protectionism. Whereas taxes or regulations are protectionist when they discourage outsiders from engaging in economic activities within a state, taxes or regulations are retentionist when then discourage in-state economic actors from engaging in out-of-state activities. As we show, the tax struck down in Wynne was both protectionist and retentionist.


dormant commerce clause, Wynne, tax discrimination, competitive neutrality, protectionism

Publication Title

Virginia Law Review

Publication Citation

103 Va. L. Rev. 309 (2017)