The Evolution of Sherman Act Case Law: A Roadmap for Competitive Federalism


For the first time in over six decades, recent Supreme Court decisions confirm that federal regulatory authority under the Commerce Clause truly is limited. These decisions coincide with an increasing appreciation among scholars and jurists for the concept of competitive federalism. This paper derives the implications of competitive federalism for federal antitrust jurisdiction under the Sherman Act. It provides a clear and substantively reasoned jurisdictional test based on the concept of geographic market power familiar to antitrust scholars, practitioners, and regulators in evaluating horizontal mergers. According to this test, to be subject to federal antitrust jurisdiction Sherman Act defendants must have a sufficiently large share of the geographic antitrust market that they can plausibly exercise market power that has a substantial effect on prices "in more states than one." This test reflects a natural progression in the evolution of Sherman Act and Commerce Clause jurisdiction. It resolves a number of troubling inconsistencies in the case law and also provides a useful roadmap for the direction the Court's general Commerce Clause jurisprudence might take in other areas of federal regulation.