an English law, passed in 1715, providing that if twelve or more persons are unlawfully assembled and disturbing the public peace they must disperse on proclamation (reading the Riot Act) or be held guilty of felony
Riot Act Idioms
read the riot act to
to command to stop doing something regarded as wrong, under threat of punishment
An English law, enacted in 1715 and repealed in 1973, providing that if 12 or more people unlawfully assemble and disturb the public peace, they must disperse after being read a specified portion of the law or be considered guilty of felony.