The Collaborative International Dictionary of English v.0.48:

Brocard \Broc"ard\, n. [Perh. fr. Brocardica, Brocardicorum
   opus, a collection of ecclesiastical canons by Burkhard,
   Bishop of Worms, called, by the Italians and French,
   Brocard.]
   An elementary principle or maximum; a short, proverbial rule,
   in law, ethics, or metaphysics.
   [1913 Webster]

         The legal brocard, "Falsus in uno, falsus in omnibus,"
         is a rule not more applicable to other witness than to
         consciousness.                           --Sir W.
                                                  Hamilton.
   [1913 Webster]