Roscoe Filburn was a small farmer in Ohio who grew wheat on his 23-acre farm. Under the Agricultural Adjustment Act of 1938, the federal government established wheat production quotas to stabilize wheat prices during the Great Depression. Filburn was allotted 11.1 acres for wheat production but planted 23 acres, producing 239 bushels more than his quota allowed.

The excess wheat was not sold in interstate commerce. Instead, Filburn used it entirely on his own farm: some for seeding future crops, some for feeding his livestock, and some for his family's consumption. The government imposed a penalty on Filburn for the excess production and ordered him to destroy the surplus wheat.

Filburn challenged the penalty, arguing that Congress lacked authority under the Commerce Clause to regulate wheat that was grown and consumed entirely within one state and never entered interstate commerce.

Congress may regulate local activities under the Commerce Clause if those activities, taken in the aggregate, have a substantial effect on interstate commerce. The substantial effects test applies even when individual activities are purely local and non-commercial.

The Commerce Clause extends to activities that are neither interstate nor commercial in character if they substantially affect interstate commerce when considered cumulatively across all similarly situated actors.

Substantial Effects Test: The Court established that Congress can regulate activities that substantially affect interstate commerce, even if the individual activity is local. The key is the cumulative effect of many similar local activities on interstate markets.

Economic Impact: Filburn's home-consumed wheat still affected interstate commerce because it satisfied his demand that would otherwise be met by purchasing wheat in the market. By growing his own wheat, he reduced demand for wheat that might have been sold in interstate commerce.

Aggregation Principle: The Court looked at the cumulative effect of all farmers growing wheat for home consumption. If many farmers exceeded their quotas for home use, it would significantly impact the interstate wheat market and undermine the federal regulatory scheme.

The Court rejected the argument that activities must be commercial or cross state lines to fall under Commerce Clause regulation, focusing instead on the practical economic effects on interstate markets.

This case marked the high-water mark of Commerce Clause expansion, establishing the substantial effects test that became the foundation for extensive federal regulation. It enabled Congress to regulate virtually any economic activity, regardless of its local nature.

The decision provided constitutional support for New Deal programs and later civil rights legislation. It established the aggregation principle, allowing regulation of individual activities that seem insignificant when viewed in isolation.

Wickard remained the dominant Commerce Clause precedent until the 1990s, when cases like United States v. Lopez began to impose some limits on federal power. However, it continues to be cited as authority for broad federal regulatory power over economic activities.