47 From what We have said, it follows that no authority whatsoever, save that which is proper to the Supreme Pastor, can render void the canonical appointment granted to any bishop; that no person or group, whether of priests or of laymen, can claim the right of nominating bishops; that no one can lawfully confer episcopal consecration unless he has received the mandate of the Apostolic See.
Source: Ad Apostolorum Principis (Vatican.va)