PLUMLEY v. MASSACHUSETTS
Plumley was convicted of violating a 1891 Massachusetts law which banned the manufacture and sale of oleomargarine colored yellow to look like yellow butter produced from pure milk.
Did the act violate the Commerce Clause?
No. The Court held that the statute did not interfere with interstate commerce but served the important function of protecting the people of Massachusetts "against fraud and deception in the sale of food products." The law did not prohibit the sale of oleomargarine, just those forms of it which were colored to look like natural butter.