In Roman law. A name applied to the Roman law of wills, in the time of Justinian, on account of its threefold derivation, viz., from the praetorian edict, from the civil law, and from the imperial constitutions. Maine, Anc. Law, 207. Jus triplex est,proprietatis, posses sionis, et possibilitatis. Right is threefold,of property, of possession, and of possibility.