In 1941 a farmer in Montgomery County, Ohio, planted 23 acres of wheat when the federal government had allotted him 11.1. He had harvested wheat from the extra 11.9 acres, wheat grown for home consumption, not for sale. The Supreme Court ruled that Washington could regulate it anyway. The reason had little to do with wheat. It was about how far federal power reaches into a state, and who gets to say.
That question is the subject of ten cases, which are better read in order than as a list. The Constitution divides power between the national government and the states without saying where one ends. The Court has drawn the line in different places at different times, and each case below moved it.
The national government is supreme in its sphere
In 1818 Maryland passed a law taxing any bank in the state that the state had not chartered. The tax applied to banks in the state not chartered by its legislature, which meant the branch of the Bank of the United States. In McCulloch v. Maryland (1819) Chief Justice Marshall held that Congress has the power to incorporate a bank and that a state cannot tax the branch. If a state could tax a federal institution, he reasoned, it could tax it out of existence, and the Union would depend on the goodwill of its members.
Five years later the Court heard a fight over steamboats. New York had given Robert Livingston and Robert Fulton the exclusive right to run steam vessels on the state's waters. Thomas Gibbons ran a boat under a federal coasting license, and Aaron Ogden, who held rights from Fulton and Livingston, sued to stop him. In Gibbons v. Ogden (1824) Marshall wrote that "commerce, undoubtedly, is traffic, but it is something more: it is intercourse." The state monopoly could not stand against a federal license.
The line moves back and forth
In 1916 Congress forbade interstate shipment of goods made by children under 14, or by older children working long hours. A father in North Carolina sued for himself and his two minor sons, one under 14 and the other between 14 and 16, to stop enforcement of the law. In Hammer v. Dagenhart (1918) Justice Day wrote that "the manufacture of goods is not commerce," so the law reached into the states' territory. Justice Holmes dissented.
Twenty-three years later the Court reversed course. United States v. Darby (1941) upheld the Fair Labor Standards Act, which set minimum wages and maximum hours for workers producing goods for interstate commerce. Justice Stone wrote for the Court, and the syllabus says plainly that Hammer was overruled. A year after that came the Ohio wheat farmer. In Wickard v. Filburn (1942) Justice Jackson wrote that his extra acres, taken with everyone else's, could affect the national wheat market, so Congress could regulate them. The commerce power now covered activity that was local and even private, as long as the effect added up.
Spending and the limits of pressure
Congress found another route: money. It told states they would lose five percent of certain federal highway funds unless they set the drinking age at 21. South Dakota, where 19-year-olds could buy 3.2 percent beer, sued. In South Dakota v. Dole (1987) Chief Justice Rehnquist wrote for a 7-2 Court that the condition was permissible. A loss of five percent of federal highway funds was, he said, not so coercive "as to pass the point at which pressure turns into compulsion." Justices Brennan and O'Connor dissented.
The Court puts limits on Congress
By the 1990s the Court was setting limits. In New York v. United States (1992) Congress had tried to deal with a shortage of disposal sites for low-level radioactive waste by offering states three kinds of incentives. The third was the "take title" provision: a state that did not arrange for its own waste by a deadline would have to take ownership of the waste and become liable for it. Justice O'Connor wrote that Congress may not "commandeer" the states' legislative processes by compelling them to enact and enforce a federal program. The first two incentives were fine; the take title provision was not.
In United States v. Lopez (1995) a 12th-grade student carried a concealed handgun into his high school and was charged under the Gun-Free School Zones Act of 1990. Chief Justice Rehnquist wrote for a 5-4 Court that the law exceeded Congress's commerce power. Two years later, in Printz v. United States (1997), Justice Scalia wrote for the same five that Congress could not order county sheriffs, such as Jay Printz of Ravalli County, Montana, and Richard Mack of Graham County, Arizona, to run background checks on handgun buyers under the Brady Act.
The Affordable Care Act
The Court's most recent word on the question came in National Federation of Independent Business v. Sebelius (2012). Chief Justice Roberts held that the individual mandate could be upheld under Congress's power to tax. On Medicaid he held that the expansion went too far: the threat to withdraw all of a state's existing Medicaid funding, over ten percent of a state's overall budget, amounted to "economic dragooning" that left states no real choice. The remedy was narrow. The Secretary could not withdraw existing funds from states that declined the expansion, and the rest of the Act stood.
Why the line keeps moving
No clause in the Constitution says how much power belongs to whom, so every generation asks again. The ten cases do show a pattern. Congress has used three tools to reach into the states: the commerce power, the spending power and direct commands. The Court allowed the first two, with limits, and has been strictest about the third. A federal law that pays a state to act is usually safe. A federal law that orders a state to act usually is not.
Sources
- McCulloch v. Maryland (1819), Gibbons v. Ogden (1824), Hammer v. Dagenhart (1918), United States v. Darby (1941), Wickard v. Filburn (1942)
- South Dakota v. Dole (1987), New York v. United States (1992), United States v. Lopez (1995), Printz v. United States (1997), National Federation of Independent Business v. Sebelius (2012)
Updated October 2026.
This post was rewritten with AI (Claude) and reviewed by an editor before publication.
