GW Law Faculty Publications & Other Works

Document Type

Article

Publication Date

2026

Status

Accepted

Abstract

The Constitution of 1787 was the instrument by which the people of the States made a partial and conditional transfer of sovereign authority to a new federal government. To preserve the States’ residual sovereignty, the Constitution established a system of conditional federal supremacy. Specifically, it made the federal government’s ability to displace of state law contingent on compliance with specific structural and procedural safeguards. The Supremacy Clause identifies only three sources of “the supreme Law of the Land”—the Constitution, laws enacted pursuant to it, and treaties made under its authority. For each of these sources of law, the Constitution specifies exclusive procedures for adoption. These structural constraints preserve residual state authority unless and until displaced by properly enacted “supreme Law of the Land.” In the absence of such law, the States retain the authority to govern matters within their own territory.

Federal courts, accordingly, possess no freestanding authority to displace governing state law absent a contrary—and valid—source of supreme law. This structural limitation, however, does not forbid judicial application of general law in all circumstances. From the founding, federal courts applied traditional branches of the law of nations—such as the law merchant, the law maritime, and the law governing sovereign relations—when state law adopted them, Congress authorized their use, or the Constitution’s structure required their application. In these contexts, federal courts acted in conformity with the lawful authority of the federal government or the States.

Federal courts were using general law in this limited, constitutionally grounded way when the Supreme Court decided Swift v. Tyson in 1842. In the second half of the nineteenth century, however, federal courts expanded their use of general law, developing a broader doctrine of “federal general common law.” They used this newly created category of law to displace state law in diversity cases without any valid source of supreme federal law authorizing them to do so. In 1938, Erie Railroad Co. v. Tompkins declared that practice unconstitutional. The Erie Court held that the federal judiciary may not invoke general common law as an independent source of authority to displace state law without a valid predicate in the Constitution or an act of Congress.

At the same time, the Supreme Court preserved the legitimate, constitutionally authorized uses of general law. On the same day that it decided Erie, the Court applied general law—recast as federal common law—to uphold the constitutional equality of the States in resolving an interstate water rights dispute. In subsequent cases, the Court confined federal common law to narrow enclaves tied to uniquely federal interests or structural features of the Constitution. The only way to make sense of these decisions, taken together, is that the Court did not repudiate all federal judicial use of general law. Rather, the Court prohibited federal courts from using general law except in the ways the Constitution permits: as interpretive context for constitutional and statutory provisions; to implement structural allocations of power; to enforce the equality and territorial integrity of the States; or when authorized by Congress or incorporated by state law.

This Article argues that recent calls to revive general common law conflate these traditional, limited uses of general law with broader categories of unwritten law that early federal courts did not apply without proper federal or state authorization. By treating general law as a freestanding source of judicial authority to displace state law, such proposals risk intruding on the residual authority of the States and circumventing the exclusive lawmaking procedures required to adopt all forms of supreme federal law. The Constitution does not permit that move. Federal courts may apply general law only when the Constitution, a valid federal statute or treaty, or state law supplies a lawful predicate. Erie recognized and restored that structural command—and remains essential to preserving the constitutional balance between national supremacy and residual state sovereignty.

GW Paper Series

2026-41

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