Is “Rule of Thumb” Really About a Wife-Beating Law? The True Origin
No such law has ever been found in English legal history. Despite being widely repeated since the 1970s in academic and popular contexts, no “rule of thumb” wife-beating statute exists in any English, Scottish, or American legal record. The phrase most likely derives from craftsmen and brewers using their thumb as a measuring instrument — a physical “rule” (measuring tool) no wider than a thumb.