In the McCray v. United States case of 1903, the Supreme Court upheld a federal law that imposed a tax on colored oleomargarine but not on uncolored oleomargarine. The plaintiff, Robert Plumer McCray, argued that this was an unconstitutional use of Congress's taxing power as it was being used to regulate state commerce and protect dairy interests against competition from manufacturers of oleomargarine. However, the court ruled in favor of the government stating that if there is any subject over which it would seem the states ought to have plenary control and be able to legislate concerning without national interference, it is when health measures are involved for protection against frauds by adulteration which directly affect people within their borders. This decision reinforced Congress's broad authority under its constitutional power to levy taxes and confirmed that such powers could be used indirectly for regulatory purposes.

In the dissenting opinion for McCray v. United States, Justice John Marshall Harlan argued that the tax on colored oleomargarine was not a legitimate exercise of Congress's taxing power but rather an unconstitutional attempt to regulate state commerce. He contended that this case represented a dangerous expansion of federal authority at the expense of states' rights and individual liberties. According to him, if Congress could use its taxing power in such a manner, it would have virtually unlimited control over all aspects of American life - something he believed was contrary to the principles upon which our nation was founded. Furthermore, he pointed out inconsistencies in how different types of oleomargarine were taxed and suggested these discrepancies revealed discriminatory intent behind legislation rather than genuine revenue-raising purpose.