According to the Korean Civil code, Art 809 and Art 815, it prohibits marriage between blood relatives i.e., they are not allowed to marry third cousins their grandparents' cousins' grandchildren or closer relatives. Art 809- states that "a marriage may not be allowed between blood relatives within the eighth degree of relationship." Art 815- declares that "a marriage is null and void if Article 809 is violated."
The Ministry of Justice is in discussion and investigation on this subject, on the scope of the ban on this consanguineous marriage following a constitutional ruling that such a provision is unconstitutional in 2022. The Constitutional Court issued the decision in a case after a man, marriage registered on May 4,2016 sought to nullify his marriage due to being within the sixth degree of blood relations second cousins with his wife. The wife appealed this decision and requested a constitutional review of the law that served grounds for the nullification of their marriage. The Constitutional Court went ahead with expressing concerns that if marriage is rendered void uniformly, after giving birth to a child and the system within, it may lead to the original legislative purpose of maintaining the functions of the family institution.
HOWEVER, the amendment discussion had invited opposition from traditionalists, particularly those who uphold Korean Confucian beliefs.
The existing laws shall remain effective until it is amended. Other reasons included genetic perspectives and international scenario, wherein the case of marriage between blood relatives, the likelihood that the child developing a genetic disease is almost the same as in the case of children from non-consanguineous marriages. Countries in similar situations like, the Germany, Switzerland and Austria now allow marriages between collateral blood relatives of fourth degree relations (cousins) or beyond. Many states of the US, the United Kingdom, France, Italy and Japan allow marriages between collateral blood relatives of fifth degree relations (second cousins).