Adultery laws were long about property and inheritance, not heartbreak
The word adultery shares its root idea with adulterate, to corrupt something pure. Old legal writers explained the link bluntly: an unfaithful wife might introduce another man's children into a husband's household and inheritance. For centuries, many laws treated the offence less as betrayal of love than as a threat to property and bloodlines.
That framing produced glaring double standards. In the Greco-Roman world, strict adultery laws applied only to sex with a married woman, so a Roman husband broke no law by sleeping with an enslaved or unmarried woman. In 1707 the English Lord Chief Justice John Holt described a man's affair with another's wife as the highest invasion of property, and the Encyclopedia of Diderot and d'Alembert in 1751 called adultery the cruellest of thefts. Minnesota's statute, repealed only in 2023, still defined the crime around a married woman.
English common law once made adultery a felony and also let a wronged husband sue the other man for damages, a civil claim called criminal conversation, conversation being an old polite word for sex. Lawyers shortened it to crim. con. England abolished the claim in 1857 and Ireland in 1976, though a few jurisdictions still allow such suits.
Since the 20th century, most Western countries have repealed criminal adultery laws, and United Nations experts argue that criminalising it violates women's rights. It still carries legal weight elsewhere: in fault-based divorce systems it is almost always grounds for ending a marriage, and even under no-fault rules it may influence property settlements or alimony. Definitions can be oddly narrow. In 2003 New Hampshire's Supreme Court, leaning on a 1961 dictionary definition of intercourse, ruled that a wife's relationship with another woman was not adultery.
How common is it? Estimates swing widely. Alfred Kinsey reported that 50 percent of American men and 26 percent of women had strayed at least once, while three nationally representative studies in the 1990s put the figures nearer 20 to 25 percent of men and 10 to 15 percent of women. A global survey by Durex found 22 percent admitting to extramarital sex.
Source: Adultery
