MANDATARIUS. One who is entrusted with and undertakes to perform a mandate. This word is used by the civilians in the same sense that we use mandatary. Poth. du Mandat, n. 1.

A Law Dictionary, Adapted to the Constitution and Laws of the United States. By John Bouvier. Published 1856.
References in periodicals archive ?
(140) In Roman law, a mandate was a gratuitous execution by one man (mandatarius, or agent) of a commission given by another (mandans or mandator, that is, principal).
This too was an offshoot of the mandate concept: the Allied Powers was the mandans and had given the mandatarius to the League.
In fact, the person, to whom this jurisdiction is transferred, is called the procurator, vicarius, substitute, or mandatarius, or even the trustee of an entrusting magistrate (1..