Blue law

Blue law, U.S. state law regulating public and private behavior in accordance with criteria of “public morality.” The term, derived from the blue paper on which some were printed, was first used to describe 17th-century laws of the New Haven Colony that prohibited dancing, card playing, and drunkenness and were particularly restrictive concerning activities that could be engaged in on Sundays. The most famous blue law (ultimately repealed) was the 18th amendment to the Constitution (1919), which made the manufacture, transport, and sale of alcoholic beverages illegal. Some states still enforce blue laws today, mostly those which regulate business and public events on Sunday. Some laws have been found to be unconstitutional under the First Amendment.