Rule of Decision Law and Legal Definition

Rule of decision refers to a rule, statute, body of law, or prior decision that provides the basis for deciding or adjudicating a case.

The following is an example of a case law on rule of decision:

In Vermont, the common law was adopted by statute; and "a rule of decision" means "the law of the state," the "foundation of our jurisprudence, and, except as modified or repealed by statute, its rules and principles determine the rights of, and prescribe rules of conduct for, all persons, and such rules and principles are to be followed and applied by our courts in all cases to which they are applicable." [Collopy v. Newark Eye & Ear Infirmary, 27 N.J. 29, 51-52 (N.J. 1958)]