AFTER 223 years New Hampshire is about to make adultery legal. A law in 1791 called for convicted adulterers to be paraded on the gallows for an hour and then “publicly whipped not exceeding 39 stripes” before being sent to prison and fined £100 (probably more than a year’s wages in those days).

The penalty has grown milder since then. Adulterers now face a $1,200 fine, which is not enforced. New Hampshire’s state House of Representatives voted to repeal the law in February; the state Senate is expected to follow soon. Not everyone is happy. A letter to the Concord Monitor huffed that adultery was “repugnant” and should remain a crime.

More than 20 states still have laws against adultery. Colorado (the state of Gary Hart, whose adultery cost him dear in the 1988 presidential race) did not decriminalise it until last year. Courts rarely hand down convictions; the most notable of recent times was in Massachusetts in 1983, when two policemen caught a married man and woman having sex in a van. They weren’t married to each other, and the woman, who challenged the charge, was fined $50.

Few Americans want the state to police their bedrooms, but 93% think adultery is morally wrong, a recent CNN poll found. That view has stiffened over the past few decades, even as attitudes to homosexuality have softened dramatically (see chart). This may be because, since the liberalising 1960s, Americans now know more about the real-world consequences of both. Many grow up at ease with gay friends but upset by their parents’ divorces.

How many Americans have strayed? In the General Social Survey, 15% of wives and 21% of husbands admitted to it. But a separate survey found that 74% of men and 68% of women said they would indulge in an affair if they knew they wouldn’t get caught. The law may no longer punish cheaters, but their spouses will if they find out.