Discrimination Against Interstate Commerce vs. Double Taxation

Daniel Shaviro

For good reasons on balance, the best academic work in tax (and other) law has moved far away in recent decades from focusing primarily on which answers to particular questions are legally correct. Not only have scholars wanted to pursue larger game than just the current, inevitably flawed, state of the law, but it is often hard to say what “legal correctness” means. Writing about policy, rather than just about legal correctness, not only broadens the menu of possible topics, but permits one to devise clearer criteria for assessing the merits of competing arguments.

There is, however, a downside to thus broadening, diversifying, and deepening the menu of favored topics. Having a positive influence on real world legal outcomes, especially if one can get there without having to tailor one’s analysis or conclusions in the manner of either a politician or a hired litigator, is both good in itself and something that we ought to care about—both as lawyers and as academics—as a matter of professional responsibility.

It is therefore a great thing to see tax academics and other members of the broader tax policy community actually swaying the outcome of a Supreme Court case in a good way. This happened in Comptroller v. Wynne, decided on May 18, 2015, in which an unusual Supreme Court majority composed of three conservatives (Alito, Kennedy, and Roberts) and two liberals (Breyer and Sotomayor) converged to strike down a Maryland income tax rule as discriminatory against interstate commerce. The majority opinion not only extensively cited work by tax scholars, but really relied on it, not just to decide the case at hand, but also to clarify the often-vexed law of how one should define discrimination under the dormant commerce clause. The Court drew on two amicus briefs (one by Michael Knoll and Ruth Mason and the other lead-authored by Alan Viard) which arose out of and/or applied academic work by both sets of authors,¹  and gave both coherent economic content and usable formulations to the potentially nebulous idea of tax discrimination. Continue reading "Discrimination Against Interstate Commerce vs. Double Taxation"