riot act
Riot Act. A 1714 English statute that made it a capital offense for 12 or more rioters to continue together for an hour after a magistrate has officially proclaimed that rioters must disperse. • This statute was not generally accepted in the United States and did not become a part of American common law. It did, however, become a permanent part of the English language in the slang phrase reading the Riot Act (meaning “to reprimand vigorously”), which originally referred to the official command for rioters to disperse.