It was not until the lex Pompeia of 52 B.C. (Dio Cassius xl. 56) had established a five years' interval between home and foreign command that the theory of the _prorogatio imperii_ vanished and the proconsulate became a separate office. Since the theory of the persistence of the republican constitution was of the essence of the Principate, the consuls necessarily lost little of their outward position and dignity under the rule of the Caesars. The consulship was the only office in which a citizen, other than a member of the imperial house, might have the princeps as a colleague, and in the interval between the death or deposition of one princeps and the appointment of another the consuls resumed their normal position as the heads of the state (cf. Herodian ii. 12). As the presidents of the senate, who after A.D. 14 elected them to their office, they were the chief personal representatives of those elements of sovereignty that were supposed to attach to that body, and they directed that high criminal jurisdiction which the senate of this period assumed (see Senate). A restored power of jurisdiction is indeed one of the features of their position during this time, and it is probable that the civil appeals which came to the senate were delegated to the consuls. They also acted for a time as delegates to the princeps in matters of Chancery jurisdiction such as trusts and guardianship (Mommsen, _Staatsrecht_, ii. p. 103). The consulship was also a preparation for certain high commands, such as the government of certain public and imperial provinces (see Province) and the praefecture of the city. It was probably due to the fact that the consulship was such a prize, and perhaps also to the expense imposed on the office by its association with the celebration of games (Dio Cassius lvi. 46, lix. 20) that the tenure was progressively shortened. In the early principate the consuls hold office for six months, later for four to two months (Mommsen, _Staatsrecht_, ii. pp. 84-87). The consuls appointed for the 1st of January were called _ordinarii_, the others _suffecti_; and the whole year was dated by the names of the former.