Under Roman civil law, which early canon law of the Catholic Church followed, couples were forbidden to marry if they were within four degrees of consanguinity. In the ninth century the church raised the number of prohibited degrees to seven and changed the method by which they were calculated. This meant that the nobility struggled to find partners to marry, as the pool of non-related prospective spouses became smaller. They had to either defy the church's position or look elsewhere for eligible marriage candidates. In 1215 the Fourth Lateran Council made what they believed was a necessary change to canon law reducing the number of prohibited degrees of consanguinity from seven back to four. The method of calculating prohibited degrees was changed also: Instead of the former practice of counting up to the common ancestor then down to the proposed spouse, the new law computed consanguinity by counting back to the common ancestor. In the Roman Catholic Church, unknowingly marrying a closely consanguineous blood relative was grounds for a declaration of nullity, but during the eleventh and twelfth centuries dispensations were granted with increasing frequency due to the thousands of persons encompassed in the prohibition at seven degrees and the hardships this posed for finding potential spouses.