— Also termed jus non scriptum; jus ex non scripto; lex non scripta; jus moribus constitutum.
“[T]he very words of the court promulgating the opinion and making the decision do not determine absolutely the rule of law but … the rule of law is ascertained by discovering what general proposition was essential to the result reached, and by using the words of the opinion as a mere aid in the ascertaining of that rule, so that, although opinions are written, the authoritative rules derived from them are sometimes not written, but are ascertained by the use of reason, causing case law to be classed as unwritten law — lex non scripta, to use the Latin phrase.” William M. Lile et al., Brief Making and the Use of Law Books 335 (3d ed. 1914).
“In the common law it is not too much to say that the judges are always ready to look behind the words of a precedent to what the previous court was trying to say, or to what it would have said if it could have foreseen the nature of the cases that were later to arise, or if its perception of the relevant factors in the case before it had been more acute. There is, then, a real sense in which the written words of the reported decisions are merely the gateway to something lying behind them that may be called, without any excess of poetic license, ‘unwritten law.’ ” Lon L. Fuller, Anatomy of the Law 145 (1968).
