PRECEDENT, n. In Law, a previous decision, rule or practice which, in the absence of a definite statute, has whatever force and authority a Judge may choose to give it, thereby greatly simplifying his task of doing as he pleases. As there are precedents for everything, he has only to ignore those that make against his interest and accentuate those in the line of his desire.

Ambrose Bierce (1842-1914?) American writer and journalist

“Precedent,” The Devil’s Dictionary (1911)
    (Source)

Originally published in the "Cynic's Word Book" column in the New York American (1906-04-06), and the "Cynic's Dictionary" column in the San Francisco Examiner (1906-04-11).