Article 38 of the Family Code enumerates the marriages that are void for being contrary to public policy. Article 38 reads:

Art. 38. The following marriages shall be void from the beginning for reasons of public policy:

(1) Between collateral blood relatives, whether legitimate or illegitimate, up to the fourth civil degree;
(2) Between step parents and step children;
(3) Between parents in law and children in law;
(4) Between the adopting parent and the adopted child;
(5) Between the surviving spouse of the adopting parent and the adopted child;
(6) Between the surviving spouse of the adopted child and the adopter;
(7) Between an adopted child and a legitimate child of the adopter;
(8) Between adopted children of the same adopter; and
(9) Between parties where one, with the intention to marry the other, killed that other person’s spouse or his or her own spouse.

[Refer also to Grounds for Declaration of Nullity of Marriage]