from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
LITIS CONTESTATIO, civil law. "Contestari." It is when each party to a suit
(uterque reus) says "Teste estote." It was therefore, so called, because
persons were called on by the parties to the suit "to bear witness," "to be
witnesses." It is supposed that this contestatio was the usual termination
of certain acts before the magistratus or in jure, of which the persons
called to be witnesses were at some future time to bear record before the
judex, in judicio. The lis contestata, in the system of Justinian, consisted
in the statements made by. the parties to a suit before the magistrate
respecting the claim or demand, and the answer or defence to it. When this
was done, the cause was ready for hearing. Savig. Traite de Droit Romain,
tom. vi. Sec. cclviii.; Smith, Dict. Gr. & Rom. Antiq. h.v. The contesting
of the suit, or pleading the general issue. Vide 2 Bro. Civ. and Adm. Law,
358.