France, Sept. 26 -- When France first legalised divorce on 20 September, 1792, it was revolution at its most intimate.

The French Revolution had begun three years earlier and was overhauling customs that had been accepted for centuries. In 1791, France's first constitution wrested marriage out of the hands of the Catholic Church and put it into the state's remit, defining it as a civil contract.

The right to break that contract came the following year, when legislators passed the country's first divorce bill.

"The right to divorce stems from individual freedom," the text read, "which would be lost if one were bound unbreakably."

Until then, couples in France could only separate, enabling them to live apart but not remarry. And while a...