At the Fourth Lateran Council (1215), the clergy reduced from seven to four the prohibited degrees of consanguinity allowed in a valid marriage, doing away with a loophole in canon law that many aristocrat couples had exploited in order to obtain a divorce:

Since therefore the prohibitions about contracting marriage in the second or third degree of affinity and about uniting the offspring of a second marriage to the kindred of the first husband frequently lead to difficulty and sometimes endanger souls, we . . . revoke with the approval of the holy council decrees published on this subject and by the present constitution decree that contracting parties connected in these ways may in future be freely united. Also the prohibition of marriage shall not in future exceed the fourth degree of the consanguinity and affinity, since in grades beyond that such prohibitions...