American federalism was a unique solution to the problem of dividing power between the government of a whole nation and the governments of the parts of that nation. Central to the acceptance of that solution was the determination, after considerable compromise, of the institution that would serve as the final arbiter of federal‐state relations. As that arbiter, the U.S. Supreme Court has on a number of occasions defined the scope and limitations of the exercise of concurrent power by the legislatures of the states and the Congress of the United States. Justice John McLean's opinion in the Passenger Cases (1849) provides a standard nineteenth‐century definition: “The general government and a State exercise concurrent powers in taxing the people of the State. The objects of taxation may be the same, but the motives and policy of the tax are different, and the powers are distinct and independent” (p. 283). McLean chose to limit state power, holding a New York state tax on immigrant passengers an unconstitutional “regulation of foreign commerce, [a power] exclusively vested in Congress” (p. 284). Similarly, the Fugitive Slave Clause (Art. IV, sec. 2) was defined as an exclusively federal responsibility in Prigg v. Pennsylvania (1842), as was sedition when the federal government alone was involved (see also Fugitive Slaves). State and federal courts share concurrent jurisdiction in a great many categories of law not denied to the states by Article III or by explicit congressional limitation, and the Supreme Court has the continuing responsibility for defining that jurisdiction.
See also Judicial Power and Jurisdiction.
— John R. Schmidhauser
