Inc. South Carolina State Highway Department v. Barnwell Bros.

The Court reaffirmed that if Congress had not specifically regulated an issue relating to interstate commerce, the states could do so, as long as their regulations did not give their own states' businesses an unfair advantage over out-of-state firms. The Court also found that a state could pass laws affecting interstate commerce, if local safety concerns outweighed any burden on that commerce.

Giving Congress the ability to regulate commerce was a top priority for the framers of the Constitution. Under the old Articles of Confederacy, the states operated almost as mini-nations, imposing tariffs on each other and issuing their own money. "Most of our political evils," wrote James Madison, "may be traced to our commercial ones." Article I, section 8 of the Constitution gives Congress the power to regulate interstate commerce, and the legislature has used the Commerce Clause broadly to achieve national goals. But that power is not absolute; the Supreme Court has found instances in which the states can still pass laws affecting interstate commerce, as in South Carolina State Highway Department v. Barnwell Bros., Inc.

In 1933, South Carolina passed a law that limited the width of trucks on its highways to 90 inches. The weight of the loads carried was also restricted, to no more than 20,000 pounds. Various truckers and shippers, including Barnwell Bros., Inc., brought suit to prevent the state from enforcing the law. The restrictions were much tougher than the ones in neighboring states and would have affected up to 90 percent of the trucks that passed through South Carolina. The district court found that the restrictions were unreasonable and a burden on interstate commerce. The court ordered South Carolina not to enforce the law.

The defendants in that trial, which included the state of South Carolina and some railway companies, then appealed to the Supreme Court. The Court, with three members absent, voted unanimously to reverse the lower court and uphold the South Carolina regulations.