Section 18Omnibus Election Code of the Philippines (Batas Pambansa Blg. 881), Sec. 18

Preservation of ballot boxes, their keys, and disposition of their contents. - Until after the completion by the Batasang Pambansa of the canvassing of the votes and until an uncontested proclamation of the President-elect and Vice-President-elect shall have been obtained, the provincial, city or district board of canvassers under the joint responsibility with the provincial, city or municipal treasurers shall provide for the safekeeping and storage of the ballot boxes in a safe and closed chamber secured by four padlocks: one to be provided by the corresponding board chairman; one by the provincial or city treasurer concerned; and one each by the ruling party and the accredited dominant opposition political party.