Latin: In Roman law. A request or petition. This was the name of the first step in a criminal prosecution, corresponding somewhat to “swearing out a warrant” in modern criminal law. The accuser appeared before the praetor, and stated his desire to Institute criminal proceedings against a designated person, and prayed the authority of the magistrate therefor. In old English ecclesiastical law. A species of petition for transfer ot a bishop. Postulatio actionis. In Roman law. The demand of an action; the request made to the praetor by an actor or plaintiff for an action or formula of suit; corresponding with the application for a writ in old English practice. Or, as otherwise explained, the actor’s asking of leave to institute his action, on appearance of the parties before the uraetor.