§1. In each diocese a presbyteral council is to be established, that is, a group of priests which, representing the presbyterium, is to be like a senate of the bishop and which assists the bishop in the governance of the diocese according to the norm of law to promote as much as possible the pastoral good of the portion of the people of God entrusted to him.
§2. In apostolic vicariates and prefectures, the vicar or prefect is to establish a council of at least three missionary presbyters whose opinion, even by letter, he is to hear in more serious matters.
Source: Code of Canon Law (Vatican.va)