We were having a conversation here in the newsroom just now and I used the phrase "reading the Riot Act" to describe one person severely reprimanding another. I started wondering where the phrase came from.
According to Wikipedia, the Riot Act, passed in the early 1700s in Great Britain, was a law that the authorities could use to break up gatherings of 12 or more people if they became disruptive. But it was required that officers read the text of the law out loud when enforcing it, sort of like reading an accused criminal his Miranda rights.
That was the literal meaning of "reading the Riot Act" to someone, and but then it eventually became a metaphor for any kind of scolding or reprimand.