In a joint session, the House of Representatives and the Senate separately approved the amendment proposed by Western Samar Rep. Antonio Nachura in Rule 8, Section 13 of the canvassing rules, prohibiting the three lawmakers from joining the panel.
Lacson ran for president while Legarda and De Castro are candidates for the vice presidency.
Lawmakers from both legislative chambers voted that the candidates who ran for the two highest elected positions of the land "will not be eligible" for inclusion in the committee.
Eastern Samar Rep. Marcelino Libanan earlier proposed that the old rules on canvassing be amended. Among the changes was the expansion of the joint canvass panel, from seven members each from the House and the Senate to 11, or a total of 22.
Both chambers voted separately to approve the expansion of the membership of the joint panel from 14 to 22.
Re-electionist senator Rodolfo Biazon said the three lawmakers should no longer be allowed to participate in floor deliberations, out of delicadeza or sense of propriety, but should now be treated as "observers to protect the credibility of the whole proceedings."
Earlier, majority of the lawmakers from both chambers thumbed down a proposal by Zamboanga City Rep. Celso Lobregat of the opposition Koalisyon ng Nagkakaisang Pilipino to abolish the joint committee and instead have the entire Congress tally the 177 certificates of canvass for the president and the vice president.
Congress should have approved the rules for the canvass last Tuesday but this was derailed when opposition Maguindanao Rep. Didagen Dilangalen raised hell after a supporter of President Arroyo sent him a note telling him to "shut up" and stop raising questions about the rules.
A heated exchange between Dilangalen and Deputy Speaker Raul Gonzalez, who was presiding over the session jointly with Senate President Pro Tempore Juan Flavier, ensued. Dilangalen and Gonzalez exchanged shouts of, "Shut up! Shut up!"
Senate President Franklin Drilon has remarked that the incident was embarrassing not only for the House but also for the entire Congress that was meeting in joint session as the National Board of Canvassers.