Lex Non Scripta

Unwritten law; the common or custom law; as opposed to lex scripta.

Matthew Hale wrote, in The History of the Common Law of England and An Analysis of the Civil Part of the Law (London: Henry Butterworth, Law-Bookseller, 1820):

"... when I call those parts of our laws (lex) non scripta, I do not mean as if those laws were only oral, or communicated from the former ages to the later, merely by word; for all those laws have their monuments in writing, whereby they are transfered from one age to another, and without which they would soon lose all kind of certainty; for as the civil ... laws have their ... determinations extant in writing; so those laws of England which are not comprised under the titles of acts of parliament, are for the most part extant in records of pleas, proceedings and judgments; in books of reports and judicial decisions; in tractates of learned men's argument and opinions, preserved from antient (sic) times, and still extant in writing."

Traditionally distinguished from lex scripta.