The Codex iuris particularis Operis Dei (Opus Dei's Statutes), which was promulgated by Saint John Paul II with the Apostolic Constitution Ut Sit on November 28, 1982, establishes that the office of the Prelate is for life. For this reason, the same norm foresees the role of the Auxiliary Vicar, which can take two forms.
The first, which is the one that concerns us now, is foreseen for cases in which, because of an increase in the work of government or the advanced age of the Prelate or other similar circumstances, the Prelate considers it advisable that, in addition to the Vicar General, whom he always must have, there be an Auxiliary Vicar who has the executive authority necessary to assist the Prelate in the government of the Prelature. Specifically, section 134.1 of the Statutes establishes that, "if the Prelate judges in the Lord that it is appropriate or useful to appoint an auxiliary Vicar in accord with n. 135, he can freely appoint one after consulting his Council. The full General Council can also sincerely suggest to the Prelate the advisability of designating an auxiliary Vicar, who can assist him in his governance for eight years. Absent grave reasons to the contrary, the Prelate should readily accept the will of the Council." With regard to the mission of this kind of Auxiliary Vicar, n.135 affirms the following: "The auxiliary Vicar, if he is given to a Prelate in possession of his faculties, assists him; if the Prelate is absent or impeded he takes his place. He has no other faculties except those which the Prelate delegates to him habitually or ad casum. He should faithfully give an account to the Prelate regarding all that he does." In the present case, the Prelate has conferred all of the powers of executive authority, including those reserved to the Prelate.
The role described here is best understood taking into account that the task which the Church entrusts to the Prelate — as with any pastor who is the head of an ecclesiastical circumscription — is not limited to the exercise of the powers of government. The prelate must also be, as the Statutes affirm, "teacher and father" (n. 132.3) for all of the faithful — both priests and laity — in his care.
The other type of Auxiliary Vicar is that foreseen in cases in which the Prelate is impeded in the exercise of his function. In such a situation, there is a procedure for the election of an Auxiliary Vicar, to whom all of the powers of the Prelate are transferred, except the title (and without the right of succession), which requires confirmation by the Holy See. In this way, even in the hypothetical case of an impeded Prelate, the role of the Prelate as Father would remain, although the government would be in the hands of the Auxiliary Vicar, whose role would be similar to that of an apostolic Administrator of a diocese.