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A sign displayed on a covered wagon, c. 1900, stating that it carried interstate commerce traffic only.
George Grantham Bain Collection/Library of Congress, Washington, D.C. (ggbain 08714)commerce clause, provision of the U.S. Constitution (Article I, Section 8) that authorizes Congress “to regulate Commerce with foreign Nations, and among the several States, and with Indian Tribes.” The commerce clause has been the chief doctrinal source of Congress’s regulatory power over the economy of the United States.
The commerce clause has traditionally been interpreted both as a grant of positive authority to Congress and as an implied prohibition of state laws and regulations that interfere with or discriminate against interstate commerce. The latter interpretation, of implied prohibition, is the so-called “dormant” commerce clause. In its positive interpretation, the commerce clause serves as the legal foundation of much of the government’s regulatory power.
In the matter of regulating commerce with foreign nations, the supremacy as well as the exclusivity of the federal government is generally understood. From time to time, state or local authorities have attempted to deal in foreign policy matters considered exclusively the province of the federal government, but their efforts have invariably been struck down by the courts. Although the states do have some limited powers to tax foreign commerce, it may generally be said that in dealings with foreign states, the federal government is the sole agent of all the people of the United States.
Congress’s use of the commerce clause to assert legislative jurisdiction in matters affecting states and their citizens has often led to disagreement about how the balance of power between the states and the federal government should be determined. The term commerce, which is not defined in the commerce clause (or anywhere else in the Constitution), has been variously interpreted by the courts. Beginning with a series of decisions in 1937, the Supreme Court has interpreted Congress’s regulatory power broadly under the commerce clause as new methods of interstate transportation and communication have come into use.
