In Cooley v. Board of Wardens (1852), a case involving a Pennsylvania pilotage law, the Court held that the power to regulate interstate commerce was not granted exclusively to the national government. In the Court's view, although some aspects of commerce necessitated uniform national rules established by Congress, other areas compelled diversity among the states and require state regulation. The Court, Justice Benjamin R. Curtis stated, needed to assess state regulations of commerce on a case‐by‐case basis, in order to decide whether the issue in question required uniformity or diversity.
This notion of the “selective exclusiveness” of congressional power under the Commerce Clause did not definitively solve the problem of allocating state and federal power over commerce. It did, however, mark a shift in the Court's approach to the issue, away from arguments over the relative sovereignty of the federal and state governments (see State Sovereignty and States' Rights) and toward a more pragmatic and economically realistic view of commercial regulation.
See also Commerce Power.
— Timothy S. Huebner
