Well, it was one of numerous "origins" listed in Wiki. , French: pouce inch/thumb; Italian: pollice inch/thumb; Spanish: pulgada inch, pulgar thumb;  Portuguese: polegada inch, polegar thumb; Swedish: tum inch, tumme thumb; Sanskrit: angulam inch, anguli finger; Slovak: palec, Slovene: palec inch/thumb, Czech: palec inch/thumb. Also in some other languages such as Thai: nîw inch/finger, Hungarian: hüvelyk inch/thumb.

"belief in the existence of a "rule of thumb" law to excuse spousal abuse can be traced as far back as 1782, the year that James Gillray published his satirical cartoon Judge Thumb."

In the United States, legal decisions in Mississippi (1824) and North Carolina (1868 and 1874) 

In 1976, feminist Del Martin used the phrase "rule of thumb" as a metaphorical reference to describe such a doctrine. "