golden rule

Noun

golden rule (plural golden rules)

1. (idiomatic) A fundamental rule or principle.
   • It is all-important to remember that naturalists have no golden rule by which to distinguish species and varieties; […]1859 November 24, Charles Darwin, “On the Imperfection of the Geological Record”, in On the Origin of Species by Means of Natural Selection, […], London: John Murray, […], →OCLC, pages 296–297
   • There is one golden rule of timetable work, that if a passenger train never runs to time it must be altered or other trains must be altered so that it can shake off its chronic unpunctuality.1943 March and April, T. F. Cameron, “The Preparation of Timetables”, in Railway Magazine, page 75
2. The principle that one should treat other people in the manner in which one would want to be treated by them.
   • "Mr. Francis seems to understand the fundamental principle of all moral accounting, the great ethic rule of three. Let A do to B, as he would have B do to him; the product will give the rule of conduct required." My father smiled at this reduction of the golden rule to arithmetical form.1818, Sir Walter Scott, chapter 2, in Rob Roy
3. (England, Wales, idiomatic) A method of statutory interpretation, whereby a judge will deviate from a literal interpretation of the law to the extent necessary to circumvent obvious absurdities or (sometimes) conclusions repugnant to public policy.