Whether marriage is annulled by the husband committing incest with his wife's sister?
Objections
❌ Objection 1 : It would seem that marriage is not annulled by the husband committing incest with his wife's sister. For the wife should not be punished for her husband's sin. Yet she would be punished if the marriage were annulled. Therefore, etc.
❌ Objection 2 : Further, it is a greater sin to know one's own relative, than to know the relative of one's wife. But the former sin is not an impediment to marriage. Therefore neither is the second.
❌ Objection 3 : Further, if this is inflicted as a punishment of the sin, it would seem, if the incestuous husband marry even after his wife's death, that they ought to be separated: which is not true.
❌ Objection 4 : Further, this impediment is not mentioned among those enumerated above (Question [50]). Therefore it does not void the marriage contract.