golden rule

noun3

1. •
   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
2. •
   The principle that one should treat other people in the manner in which one would want to be treated by them.
3. •
   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.