The Riot Act was passed in 1715 in response to the increasing number of mobs seen in Britain. Catholic Jacobites rioted in opposition to the new Hannoverian King George I so Parliament hastily pushed through a draconian law preventing groups of 12 or more from assembling “unlawfully and riotously.”
When such a crowd began to gather, a public official would have to stand before them – either a brave or foolhardy thing to do – and read the following proclamation of the Riot Act:
“Our sovereign Lord the King chargeth and commandeth all persons, being assembled, immediately to disperse themselves, and peaceably to depart to their habitations, or to their lawful business, upon the pains contained in the act made in the first year of King George, for preventing tumults and riotous assemblies.
God save the King.”
Any people who remained were subject to severe punishments including prison sentences or hard labour.
The most infamous use of the law was during the Peterloo Massacre at St Peter’s Field, Manchester, on 16 August 1819. Campaigners gathered peacefully, demanding the right to vote, but local magistrates watching from a nearby window panicked. The Riot Act was read, but could only be heard by the few people close to the speaker. When the crowds did not disperse, a cavalry unit charged and an estimated 18 people were killed.
The unusual sight of a man standing before a crowd and reading a proclamation led the expression, ‘read the Riot Act’, to become popularly used to reprimand or warn – although not necessarily to a mob.