From the Council of Orleans, A.D. 533

Canon X. Let no one be joined by any coupling to his own stepmother, that is, to the wife of his father. But if anyone has presumed this, let him know that he is to be struck with the punishment of anathema.

Canon XI. Contracted marriages, when infirmity supervenes, are not dissolved by any contrariety of will. But if any of the spouses have done so, let them know that they are to be deprived of communion.

Even if the infirmity is impotence for coition, or brings this about, still, if it is consequent, it does not dissolve the bond.

Canon XIX. It has pleased us that no Christian shall take a Jewish woman as wife in marriage, nor a Jew a Christian woman; because we judge that between persons of this sort there are illicit nuptials. But if, after being admonished, they delay separating themselves from this consortship, they are without doubt to be removed from the grace of communion.

Since separation without any hope of return is prescribed under penalty of excommunication, it is ready to understand that the Fathers wished these nuptials to be held as null; therefore the illicit nuptials here are also invalid. You have the impediment of disparity of cult. But the law is not of the universal Church, but is particular to the Gallican province. Cf. Canon XIV of the Council of Chalcedon, above.