From the Council of Leptines, with Boniface and Two Others, Legates of the Apostolic See, Presiding, A.D. 745

Canon III. We prescribe that, according to the decrees of the canons, adulteries and incestuous marriages, which are not legitimate, be prohibited.

Canon V. If anyone has held his stepson or stepdaughter before the bishop for confirmation, let him be separated from his wife and not accept another (from Fulbert of Chartres, Epistle 33).

Canon VI. Let no one receive his own son or daughter from the font of baptism; nor let him lead as wife his goddaughter or the mother, nor her whose son or daughter he has held for confirmation. But where this has been done, let them be separated (from the same).

Canon VII. If a man is not able to render the conjugal debt to a woman betrothed, dowered, and led in public nuptials, according to the Apostle, and this has been made manifest either by the confession of both or by any certain proof, let them be separated; and let the woman, if she cannot contain herself, lawfully marry another man (from Epistle 22 of Hincmar of Reims to Hrodulf).

Cf. Response II of Gregory II in his epistle to Boniface.