The constitutional rationale of Erie Railroad Co. v. Tompkins has remained elusive for almost seventy years. Three decades ago, Paul Mishkin argued in a brief but influential article that Erie rests on "constitutional principles which restrain the power of the federal courts to intrude upon the states' determination of substantive policy in areas which the Constitution and Congress have left to state competence." Professor Mishkin wrote his article in response to John Hart Ely's insightful analysis of Erie published earlier the same year. Mishkin understood Erie as imposing a constitutional restraint on the federal courts, but read Ely as treating "the Constitution as relevant only in terms of Congress' power to displace state substantive law" and not as an independent restriction on "the power of the federal courts to do so." Mishkin grounded his contrary understanding "on the structure established by the Constitution whereby the states, and their interests as such, are represented in the Congress but not in the federal courts." Invoking the separation of powers, Mishkin concluded that "the Constitution bears not only on congressional power but also imposes a distinctive, independently significant limit on the authority of the federal courts to displace state law."
Professor Mishkin's article remains a key reference in the field because scholars continue to debate the precise contours - and even the existence - of the constitutional basis for the Supreme Court's decision in Erie. Mishkin's unique contribution was to link federalism with the constitutional separation of powers. This account of Erie's constitutional rationale is insightful and, in my view, correct. It may be fortified, however, by an additional structural argument that ties Erie directly to the Supremacy Clause. That Clause recognizes only the "Constitution," "Laws," and "Treaties" as "the supreme Law of the Land," and thus incorporates three distinct sets of federal lawmaking procedures found elsewhere in the Constitution. By design, all of these procedures safeguard federalism by requiring the participation and assent of the states or their representatives in the Senate. Accordingly, the constitutional structure strongly suggests that the Supremacy Clause establishes the exclusive basis for disregarding state law, and that more expansive judicial doctrines like Swift are unconstitutional. Reliance on these features of the constitutional structure is implicit in the Erie opinion and provides formal substantiation of Professor Mishkin's sound intuitions about Erie, the separation of powers, and federalism.
GW Paper Series
GWU Legal Studies Research Paper No. 259; GWU Law School Public Law Research Paper No. 259
Bradford R. Clark, Erie's Constitutional Source, 95 Cal. L. Rev. 1289 (2007).