What is Jus Quiritium?

Legal Definition
The old law of Rome, that was applicable originally to patricians only, and, under the Twelve Tables, to the entire Roman people, was so called, in contradistinction to the jus proetorium, (q. v.,) or equity. Brown.
-- Black's Law Dictionary
Legal Definition
The Roman law which at first extended only to the patricians, but later to the whole Roman people.
-- Ballentine's Law Dictionary