Administrative Code of 1987
Section 5. Who are Citizens. - The following are the citizens of the Philippines:
(1) Those who are citizens of the Philippines at the time of the adoption of the Constitution;
(2) Those whose fathers or mothers are citizens of the Philippines;
(3) Those born before January 17, 1973, of Filipino mothers, who elect Philippine citizenship, unless by the act or omission they are deemed, under the law, to have renounced it.
(4) Those who are naturalized in accordance with law.