Section 19Omnibus Election Code of the Philippines (Batas Pambansa Blg. 881), Sec. 19

When certificate of canvass is incomplete or bears erasures or alterations. - When the certificate of canvass, duly certified by the board of canvassers of each province, city or district in Metropolitan Manila and transmitted to the Speaker of the Batasang Pambansa, as provided in the Constitution, appears to be incomplete, the Speaker shall require the board of canvassers concerned to transmit to his office, by personal delivery, the election returns from polling places that were not included in the certificate of canvass and supporting statements. Said election returns shall be submitted by personal delivery to the Speaker within two days from receipt of notice.

When it appears that any certificate of canvass or supporting statement of votes by polling place bears erasures or alterations which may cast doubt as to the veracity of the number of votes stated therein and may affect the result of the election, the Batasang Pambansa upon request of the Presidential or Vice-Presidential candidate concerned or his party shall, for the sole purpose of verifying the actual number of votes cast for President or Vice-President, count the votes as they appear in the copies of the election returns for the Commission. For this purpose, the Speaker shall require the Commission to deliver its copies of the election returns to the Batasang Pambansa.