In the case of Wilson & Co., Inc. v. United States in 1940, the U.S Supreme Court ruled that a federal tax on oleomargarine did not violate the Fifth Amendment's due process clause or constitute an unlawful delegation of legislative power to administrative agencies. The court held that Congress had broad discretion to impose taxes and could delegate authority to determine tax rates within defined limits set by law. In this case, Congress had imposed a higher tax rate on colored oleomargarine than uncolored margarine and delegated authority to the Commissioner of Internal Revenue to establish regulations for determining whether margarine was "artificially colored." The plaintiff, Wilson & Co., argued this constituted arbitrary discrimination and excessive delegation of legislative power but these arguments were rejected by the court.

In the dissenting opinion for Wilson & Co., Inc. v. United States, it was argued that the majority's decision to uphold a tax on oleomargarine violated principles of federalism and exceeded Congress' power under the Commerce Clause. The dissenting justices believed that this case represented an overreach by the federal government into areas traditionally regulated by states, such as public health and safety regulations related to food products. They also expressed concern about potential implications for other industries if Congress could impose taxes based on product characteristics or manufacturing processes rather than their interstate commerce activities. Furthermore, they disagreed with the majority's interpretation of "filled milk" in relation to oleomargarine production and its impact on dairy industry competition.