Short answer. No. First cousins are collateral blood relatives in the fourth civil degree, and the Family Code voids marriages between collateral blood relatives up to that degree for reasons of public policy. The marriage is void from the beginning, whether or not anyone objects to it.
What the law says
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;
Family Code, Article 38 — Marriages Void for Public Policy. Read the full provision →
Why cousins fall inside the fourth degree
Collateral relatives are counted by going up from one person to the common ancestor and back down to the other, one degree per generation each way. From you to your parent is one, to your grandparent is two, down to your uncle or aunt is three, and down again to their child, your first cousin, is four. First cousins therefore sit exactly on the outer edge of the prohibition, which covers relatives up to the fourth civil degree. Second cousins, whose count runs to six, fall outside it. The distinction is arithmetic, not sentiment about how close the families are.
Legitimacy and half-blood make no difference
The clause voids marriages between collateral blood relatives whether legitimate or illegitimate. A cousin through a parent's non-marital child is caught in the same way as a cousin through a marriage, and a half-blood relationship counts as a blood relationship for this purpose. What the provision looks for is the blood link and the number of degrees, so a family that never acknowledged the connection, or a registry entry that does not show it, does not make the marriage valid. It only makes the defect harder for a registrar to notice at the counter.
Void from the beginning, and it stays that way
This is not a marriage a court may annul at somebody's option. It is void from the beginning, meaning no valid marriage ever came into existence. Living together for decades does not ratify it, having children does not cure it, and neither does a licence issued in ignorance of the relationship. The practical consequences surface late and painfully: a survivor claiming as a spouse, a party seeking to remarry, or heirs contesting an estate will each run into the same finding. Property acquired during the union is then sorted out under the rules for unions without a valid marriage.
What to establish before anything else
Trace the line on paper rather than from memory. Birth certificates for both parties and for their parents will usually show whether a common grandparent exists, which is the fact the whole question turns on. Where an ancestor's records are missing or names were changed, that gap is worth resolving early, because the question will be asked again by anyone who later has reason to challenge the union. If the relationship is more distant than you think, that is worth confirming too. Take the certificates, not a family tree drawn from recollection, when you consult a lawyer.
Cases citing this provision
These Supreme Court decisions cite the provision above. We list them so you can read them yourself; the summaries of what each decided are not ours to give.
- Republic of the Philippines vs. Marelyn Tanedo Manalo, G.R. No. 221029, April 24, 2018 — read the decision on LawPhil →
- Abigael An Espina-dan vs. Marco Dan, G.R. No. 209031, April 16, 2018 — read the decision on LawPhil →