Today, “reading the riot act” means warning an unruly citizen, or citizens, to stop behaving badly.
An actual Riot Act was passed by the British government in 1714 and came into force in 1715. Under this English law, any group of twelve or more persons that worried the authorities could be deemed a “riotous and tumultuous assembly” and arrested if they didn’t disperse within an hour of the Riot Act being read to them by a magistrate. If not, their just punishment would be prison, labor, or death. This seems harsh to us now but, in the 1700s, the government was fearful of Catholic Jacobite mobs who threatened to overthrow George I.
The fear was well-founded, as supporters of the deposed Stuarts did actually invade in 1715 and again in 1745. The Riot Act, which was more formally called “An act for preventing tumults and riotous assemblies,” and for the more speedy and effectual punishment of the rioters actually contained this warning: “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.”
It was, apparently, crucial to read the Act aloud in order to serve formal notice that the parties involved were overstepping their bounds. Punishment for ignoring the Act was severe — penal servitude for not less than three years, or imprisonment with hard labor for up to two years.
After the Hanoverians were established in power, the Riot Act began to fall into disuse. It was read to a group of demonstrating mill workers at Manchester Town Hall in 1842, but was used with decreasing frequency and had become a rarity by the 1900s. However, the Act wasn’t formally repealed until 1973.
The first record of the figurative use of the phrase is in William Bradford’s Letters, December 1819: “She has just run out to read the riot act in the Nursery.”
Wikipedia tells me that Acts similar to the Riot Act passed into the law of countries such as Australia, Canada, and the United States, all at the time colonies of Great Britain, and in several of them such provisions, in their original or modified forms, remain as law today.
It doesn’t do me the slightest bit of good to read the riot act to April, my calico cat. On the other hand, it doesn’t do her any good to read it to me, so I suppose we’ll just go on enjoying the stalemate.