“To illustrate the misogynous underpinnings of our society, analysts have referred to the ‘rule of thumb’ by which English and American law as recently as the 18th and 19th century reputedly upheld the right of a man to beat his wife with a rod, provided it was no thicker than his thumb….
“The rule was originally asserted in England by Judge Buller in 1783 — but English legal authorities challenged him and writers and cartoonists lampooned him.
“Some scholars have asserted that the rule of thumb became incorporated into American law… and a ruling by the State Supreme Court of North Carolina is cited. However, closer inspection reveals that the court repudiated both the right of a husband to beat his wife and specifically the rule of thumb, even ridiculing the latter….
“Although the court did uphold the lower court’s ruling that the husband who had struck his wife with ‘three licks’ from a ‘switch about the size of one of his fingers’ had not violated the law, the judges emphasized that their grounds were ‘not that the husband has the right to whip his wife much or little; but that we will not interfere with family government in trifling cases.’ ”
— From “Handbook of the Sociology of Gender” by Janet Saltzman Chafetz (2006)