Rule of thumb
The error appeared in a number of law journals, and the United States Commission on Civil Rights published a report on domestic abuse titled "Under the Rule of Thumb" in 1982.
During the 1990s, several authors correctly identified the spurious folk etymology; however, the connection to domestic violence was still being cited in some legal sources into the early 2000s.
This belief may have originated in a rumored statement by 18th-century judge Sir Francis Buller that a man may beat his wife with a stick no wider than his thumb.
Wife-beating has been officially outlawed for centuries in England and the United States, but continued in practice; several 19th-century American court rulings referred to an "ancient doctrine" that the judges believed had allowed husbands to physically punish their wives using implements no thicker than their thumbs.
[11][12][13] A modern folk etymology[14] relates the phrase to domestic violence via an alleged rule under English common law which permitted wife-beating provided that the implement used was a rod or stick no thicker than a man's thumb.
[7][a] Twentieth-century legal scholar William L. Prosser wrote that there was "probably no truth to the legend" that a husband was allowed to beat his wife "with a stick no thicker than his thumb".
[3][7][16] In the following century, several court rulings in the United States referred to a supposed common-law doctrine which the judges believed had once allowed wife-beating with an implement smaller than a thumb.
[3] An 1824 court ruling in Mississippi stated that a man was entitled to enforce "domestic discipline" by striking his wife with a whip or stick no wider than the judge's thumb.
[5] While Martin appears to have meant the phrase rule of thumb only as a figure of speech, some feminist writers treated it as a literal reference to an earlier law.
[5][10]: 43 The following year, a book on battered women stated: One of the reasons nineteenth century British wives were dealt with so harshly by their husbands and by their legal system was the 'rule of thumb'.
[5] During the 1990s, several authors wrote about the false etymology of rule of thumb, including English professor Henry Ansgar Kelly and conservative social critic Christina Hoff Sommers,[3] who described its origin in a misunderstanding of Blackstone's commentary.
