Until South Korea's Constitutional Court ruled on 26 February 2015 to abolish the crime, adultery was a criminal offence in South Korea and had been since 1953.
A report in the Korea Times says:
The first adultery case involving celebrities was in 1960 involving actor Choi Moo-ryong and actress Kim Ji-mi. The couple were in a relationship outside of marriage. In 1970, a local TV station famously aired video footage of the well-known actress Chung Yoon-hui in a jail cell for committing adultery.
The JD Journal quotes five of the nine justices on the court as saying:
It has become difficult to say that there is a consensus on whether adultery should be punished as a criminal offense. It should be left to the free will and love of people to decide whether to maintain marriage, and the matter should not be externally forced through a criminal code.
As the headline in the New York Times article has it,
Adultery Is No Longer an Affair of the State in South Korea.
What good headline, with the unspoken link to 'affairs of the heart'.
As for actual numbers, The Guardian reports that:
In the past six years, close to 5,500 people have been formerly arraigned on adultery charges - including nearly 900 in 2014.
But the numbers had been falling, with cases that end in prison terms increasingly rare.
Whereas 216 people were jailed under the law in 2004, that figure had dropped to 42 by 2008, and since then only 22 have found themselves behind bars, according to figures from the state prosecution office.
The maximum sentence for the offence under the law was two years. That said, South Korea was not the only country to have criminalised adultery Taiwan’s Criminal Code Article 239 provides that "married spouses who commit adultery be imprisoned for up to one year."
The Backdrop To The Creation Of The Offence In 1953
The Korean War lasted from 25 June 1950 – 27 July 1953. I can't help but wonder what relationship there is between the origin of the statute and the Korean War.