The distinction between natural butter artificially colored, and oleomargarine artificially colored so as to cause it to look like butter…was held to be so marked, and the aptitude of oleomargarine when artificially colored to deceive the public into believing it to be butter was decided to be so great, that it was held no violation of the due process clause of the Fourteenth Amendment was occasioned by state legislation absolutely forbidding the manufacture, within the State, of oleomargarine artificially colored. As it has been thus decided that the distinction between the two products is so great as to justify the absolute prohibition of the manufacture of oleomargarine artificially colored, there is no foundation for the proposition that the difference between the two was not sufficient, under the extremest view, to justify [tax rates] distinguishing between them.
…that is, that the manufacture of artificially colored oleomargarine may be prohibited by a free government without a violation of fundamental rights.
From McCray v. United States (1904), one of the most turgidly written Supreme Court decisions I’ve ever read, but not without its unintentional moments of comedy gold.
For the record, McCray was arguing that the only artificial coloring in his oleomargarine came from the artificial coloring used in the butter that was one of the ingredients, which he claimed was added to most butter produced in the U.S. to ensure the deep yellow color preferred by customers.