The power of Congress to regulate interstate commerce extends to a restaurant that is not patronized by interstate travelers but which serves food that has moved in interstate commerce. This ruling makes the Civil Rights Act of 1964 apply to virtually all businesses. Decided December 14, 1964 (argued October 5, 1964). Opinion of the Court: Thomas Campbell Clark → go there Topic: Power of Congress to enforce civil rights. Katzenbach v. McClung, 379 U.S. 294 (1964), is a landmark decision of the U.S. Supreme Court which unanimously held that Congress acted within its power under the Commerce Clause of the United States Constitution in forbidding racial discrimination in restaurants as this was a burden to interstate commerce. Wiki link