10/09/2026
The Senate Impeachment Court is seeking guidance from four retired Supreme Court justices on a constitutional question that could directly affect Vice President Sara Duterte’s impeachment trial: Does conviction always require 16 votes even when some senators cannot participate?
Retired Chief Justices Artemio Panganiban and Reynato Puno and retired Associate Justice Adolf Azcuna have been invited to appear as amici curiae, or friends of the court, on Sept. 16. Former Chief Justice Hilario Davide Jr. will instead submit a legal memorandum.
“The Impeachment Court is not leaving constitutional math to guesswork or chance,” court spokesperson Atty. Regie Tongol said.
The issue stems from an appeal by Senator-Judge Erwin Tulfo questioning whether senators who are unable to participate should still be counted in determining the two-thirds vote required for conviction.
The Constitution states that conviction requires the concurrence of “two-thirds of all the Members of the Senate.” With a full 24-member Senate, that has traditionally meant 16 votes.
But Tulfo’s appeal raises a potentially consequential question: What happens when some senators remain members of the chamber but cannot take part in the trial?
The invited former justices will provide independent legal guidance and may answer clarificatory questions from senator-judges. They will not be cross-examined by either side.
The House prosecution and Duterte’s defense are scheduled to present oral arguments on Sept. 23 before the senator-judges vote on the appeal.
The eventual ruling could affect not only Duterte’s trial but also how voting thresholds are calculated in future impeachment proceedings.
For now, the impeachment court’s existing rule requiring 16 votes to convict remains in effect.
