22 Furthermore, after all power had devolved upon the Christian emperors, the supreme pontiffs and bishops assembled in council persisted with the same independence and consciousness of their right in commanding or forbidding in regard to marriage whatever they judged to be profitable or expedient for the time being, however much it might seem to be at variance with the laws of the State. It is well known that, with respect to the impediments arising from the marriage bond, through vow, disparity of worship, blood relationship, certain forms of crime, and from previously plighted troth, many decrees were issued by the rulers of the Church at the Councils of Granada,(40) Arles,(41) Chalcedon,(42) the second of Milevum,(43) and others, which were often widely different from the decrees sanctioned by the laws of the empire. Furthermore, so far were Christian princes from arrogating any power in the matter of Christian marriage that they on the contrary acknowledged and declared that it belonged exclusively in all its fullness to the Church. In fact, Honorius, the younger Theodosius, and Justinian,(44) also, hesitated not to confess that the only power belonging to them in relation to marriage was that of acting as guardians and defenders of the holy canons. If at any time they enacted anything by their edicts concerning impediments of marriage, they voluntarily explained the reason, affirming that they took it upon themselves so to act, by leave and authority of the Church,(45) whose judgment they were wont to appeal to and reverently to accept in all questions that concerned legitimacy(46) and divorce;(47) as also in all those points which in any way have a necessary connection with the marriage bond.(48) The Council of Trent, therefore, had the clearest right to define that it is in the Church's power "to establish diriment impediments of matrimony,"(49) and that "matrimonial causes pertain to ecclesiastical judges."(50)
Source: Arcanum Divinae (Vatican.va)