4 When have you heard, most gracious Emperor, that laymen gave judgment concerning a bishop in a matter of faith? Are we so prostrate through the flattery of some as to be unmindful of the rights of the priesthood, and do I think that I can entrust to others what God has given me? If a bishop is to be taught by a layman, what will follow? Let the layman argue, and the bishop listen, let the bishop learn of the layman. But undoubtedly, whether we go through the series of the holy Scriptures, or the times of old, who is there who can deny that, in a matter of faith,—in a matter I say of faith,—bishops are wont to judge of Christian emperors, not emperors of bishops.
Source: Letters (New Advent)