The Senate should amend its rules to allow absent senator-judges to participate in the impeachment trial before changing the number of votes needed to convict Vice President Sara Duterte, her spokesperson Salvador Paolo Panelo Jr. said Wednesday.

Panelo made the challenge after the Senate impeachment court voted to lower the voting threshold by limiting the constitutional phrase “all the Members of the Senate” to senator-judges actively participating in Duterte’s trial.

“If what they want is fairness, that only the senators that can vote are those that are able to participate, then they should exhaust all of their remedies to make sure that their colleagues are present or at least accounted for by video conference,” Panelo told reporters at the Senate.

The court voted 13-1, with six senator-judges not participating, to adopt the new interpretation.

Presiding Officer Francis “Chiz” Escudero initially interpreted the provision to require 16 votes, based on the full 24-member Senate.

The threshold was later challenged after a senator-judge became unable to participate in the trial, prompting Sen. Erwin Tulfo to seek reconsideration of Escudero’s ruling.

The dispute centers on Article XI, Section 3(6) of the 1987 Constitution, which says an impeached official cannot be convicted without the concurrence of two-thirds of all the members of the Senate.

Panelo maintained that the Constitution makes no distinction between senators who participate in the impeachment trial and those who do not.

“Wala naman pong ganong distinction sa Konstitusyon,” he said.

He also pointed to the framers’ choice of the phrase “all the Members” rather than language referring to members who are present, arguing that the distinction was deliberate.

Last week, retired Supreme Court chief justices Artemio Panganiban, Reynato Puno and Hilario Davide Jr. said the two-thirds requirement should be based on senator-judges who actively participated in the trial.

Former Supreme Court Associate Justice Adolfo Azcuna, one of the framers of the 1987 Constitution, disagreed, saying the requirement should remain based on the Senate’s entire membership.

House prosecutors have backed a calculation based on senators capable of participating in the impeachment proceedings.

House prosecutor Rep. Chel Diokno argued Wednesday that using all 24 senators as the denominator could result in an “acquittal by default” if senators unable to perform their functions as impeachment judges are still counted.

Panelo, however, accused the Senate majority of trying to lower the threshold because it could not secure 16 votes to convict Duterte.

He described the move as an attempt to “manufacture” a conviction, a claim made by the defense that was not independently established.

Panelo also argued that changing the interpretation of a constitutional supermajority requirement could set a precedent for other votes requiring a specified number of lawmakers.

He cited constitutional amendments as an example, asking whether lawmakers could similarly be excluded from the computation of future supermajority votes simply because they could not participate.

Earlier Wednesday, the impeachment court voted 13-6, with one abstention, to reject Sen. Alan Peter Cayetano’s attempt to stop the threshold issue from being taken up.

Cayetano had argued that the threshold should not be changed midway through the trial and said he and other senator-judges might not participate in the threshold vote.

Panelo said that earlier vote should not necessarily be interpreted as an indication of how senators would vote on the threshold itself.

He nevertheless pointed to the 13 affirmative votes and suggested that they could indicate the number of senators who might support a lower conviction threshold, while acknowledging that the vote was technically on a different question.

“Pero, di ba, huwag natin silang pamunahan. Baka naman ang pinagbutuhan lang kanina is whether the Senate has the power to proceed to this voting threshold. So, let's give them the benefit of the doubt,” Panelo said.