Wickard v. Filburn (1942) stands for the principle that Congress has very broad power to regulate commerce—even commerce that would appear to not meet any definition of interstate commerce.

Roscoe Filburn, a farmer who raised chicken and cattle, planted 12 more acres of wheat than he was supposed to under the Agricultural Adjustment Act of 1938. The federal law was designed to control the volume of wheat in commerce to ensure there were no surpluses or shortages that would lead to abnormally high or low wheat prices. Government officials fined Filburn because he produced 239 more bushels than he was allotted under the law. Filburn challenged the fine, contending that Congress exceeded its powers under the Commerce Clause in punishing him for wheat that he did not even sell in interstate commerce. Filburn argued that the Commerce Clause did not give Congress the power to regulate local, intrastate acts that have only an indirect effect on commerce. He sued several federal officials, including Claude R. Wickard, the U.S. secretary of agriculture from 1940 to 1945.

The Supreme Court unanimously ruled 8–0 against Filburn. The Court reasoned that while Filburn’s own wheat production may have been trivial, his production when added with the production of other small wheat farmers was “far from trivial.” The Court noted that those who produce their own wheat do affect interstate commerce by, at the very least, removing many potential customers for wheat: “Home-grown wheat in this sense competes with wheat in commerce.” The Court also noted that Congress was in a far better position to pass laws dealing with the wheat industry which “has been a problem industry for some years.”