Which case established that the federal government can regulate purely local activities only if they have a substantial effect on interstate commerce?

• A. Heart of Atlanta Motel v. United States (1964)
• B. Wickard v. Filburn (1942)
• C. United States v. Lopez (1995)
• D. Gonzales v. Raich (2005)

Answer: (B)

The key idea is the reach of the Commerce Clause when dealing with local activities. Wickard v. Filburn establishes the aggregation principle: Congress can regulate a local activity if, in the aggregate with similar activities, it has a substantial effect on interstate commerce. In the case, a farmer grew wheat for personal use. Although that wheat wasn’t sold, the Court held that regulating such production was permissible because if many farmers did the same, it could alter prices and supply in interstate markets. The decision anchors the view that small, local actions can be regulated because their combined impact on the national economy is substantial. Other cases illustrate related limits or applications, but Wickard is the foundational case for the substantial-effects test.