heraldic image
Wikimedia Commons

The Act for suppressing the detestable sins of Incest, Adultery, and Fornication, commonly known as the Commonwealth (Adultery) Act, was passed by the Rump Parliament of the Commonwealth of England in 1650, a year after the execution of King Charles I. Among other things, it represented an attempt by the state to wrest control of the enforcement of sexual morality from the Church.[1] The historian Bernard Capp has called the Act “the most notorious legislation of the interregnum”.[2]

The view of the Church since at least the time of St Augustine (354–430 AD) had been that sexual desire had to be controlled through marriage, into the “relatively safe channel of monogamy”. Sexual pleasure was so dangerous that even sexual positions had to be considered; only the missionary position was acceptable, as it was thought to be the least pleasurable for women. Sex was for procreation, not for pleasure. Sexual deviance, which included non-penetrative acts and fornication – sexual intercourse outside marriage – were punished by the Church courts, until the Act of 1650 made it a secular offence punishable for married women by death.[3]

Fornication and adultery

Any man, married or otherwise, who had “carnal knowledge of the body of any Virgin, unmaried Woman or Widow”, was guilty of fornication, and subject to three months in prison for a first offence. A married woman on the other hand, who “be carnally known by any man (other them her Husband)” was subject to the death penalty, as was her lover. Exceptions were made for the victims of rape, and for those women whose husbands had been absent for three years or more.[4] Perhaps at least in part because of the ferocity of the new law, and the consequent unwillingness of some judges and juries to convict, the number of cases of adultery brought before the courts decreased after 1650 compared with the number that had been dealt with by the Church courts.[5] But a significant problem for the courts was to determine whether or not a marriage had taken place, as until the passing of the Marriage Act of 1753 a formal ceremony of marriage before a clergyman was not a legal requirement in England, and marriages were unregistered.[6]


Prosecutions for incest under the new law were rare. One early case was that of William Frodsham, who had married an elderly widow. Following her death he married her daughter, for which he was condemned to death at Chester Assizes in 1653, although it seems likely that he was reprieved. The previous year a man in Norfolk had been publicly whipped for sharing a bed with his daughter, despite there being no evidence of any sexual impropriety. Similar cases had come before the Church courts, and usually resulted in a warning.[5]


Following the Restoration of the monarchy in 1660, the Commonwealth (Adultery) Act was declared void, along with every other Act of Parliament passed during the interregnum, as they had not received royal assent.[7]



British History Online. May 1650: An Act for Suppressing the Detestable Sins of Incest, Adultery and Fornication. https://www.british-history.ac.uk/no-series/acts-ordinances-interregnum/pp387-389.
Bryce, James. Studies in History and Jurisprudence. Oxford University Press, 1901.
Capp, Bernard. England’s Culture Wars: Puritan Reformation and Its Enemies in the Interregnum, 1649–1660. Oxford University Press, 2012.
Millar, Charlotte-Rose. “Sleeping with Devils: The Sexual Witch in Seventeenth-Century England.” Supernatural and Secular Power in Early Modern England, edited by Marcus Harmes and Victoria Bladen, Ebook, Routledge, 2015.
Weinstein, Jeremy D. “Adultery, Law, and the State.” Hastings Law Review, vol. 38, no. 1, 1986, pp. 195–238, https://repository.uchastings.edu/hastings_law_journal/vol38/iss1/3.