United States v. Bass

In United States v. Bass, 404 U.S. 336, 349 (1971), the U.S. Supreme Court strengthened principles of federalism by declaring that:

Unless Congress conveys its purpose clearly, it will not be deemed to have significantly changed the federal-state balance.

The Court relied on Congress' failure to make a clear statement of its intention to alter the federal-state balance, in order to construe an ambiguous firearm-possession statute to apply only to firearms affecting commerce. Id. at 349-50.