Sara Duterte Impeachment Trial — September 16, 2026

 

Sara Duterte Impeachment Trial on September 16, 2026: Retired Justices Split Over the Conviction Vote Threshold

The Senate impeachment court took a break from regular evidence presentation on Wednesday, September 16, 2026, to hear legal opinions on one of the trial’s most consequential procedural questions: how many senators must vote to convict Vice President Sara Duterte?

Three retired Supreme Court justices appeared as amici curiae, or “friends of the court.” Retired Chief Justices Artemio Panganiban and Reynato Puno and retired Associate Justice Adolfo Azcuna answered questions from the senator-judges. Retired Chief Justice Hilario Davide Jr. sent his views in a written memorandum after a recent medical procedure. 

The justices were invited to assist the court—not to decide whether Duterte committed any of the allegations against her. Their discussion concerned the interpretation of the constitutional two-thirds requirement and the participation of senator-judges.

Why the court paused the trial

The session followed Sen. Erwin Tulfo’s appeal of Presiding Officer Chiz Escudero’s earlier ruling that 16 of the 24 senators would be needed to convict. The appeal raised questions about whether the denominator should always be the full 24-member Senate or only the senators legally and physically able to participate in the impeachment proceedings.

The court asked the amici to address three related issues:

1. Whether “two-thirds of all the Members of the Senate” means two-thirds of all 24 senators or two-thirds of the senators qualified to participate and vote.
2. Whether the 1949 Supreme Court decision in Avelino v. Cuenco—which dealt with a senator beyond the Senate’s power to compel attendance—could guide the impeachment court’s treatment of senators who are detained, abroad, suspended, or whose whereabouts are unknown.
3. Whether a senator-judge who did not attend or substantially participate in the trial could still vote on the final verdict.

Because the focus was constitutional interpretation, there was no ordinary witness testimony or new financial evidence presented on September 16. The day was about the rules that could govern the eventual vote, not the factual merits of the impeachment charges.

Three justices favored a flexible threshold

Davide, Panganiban, and Puno generally agreed that the two-thirds requirement should not automatically remain a fixed 16 votes in every possible circumstance. Their advice was that the court may need to count only senators who are legally capable of performing their duties in the impeachment case.

Davide: count senators qualified to vote

In his memorandum, Davide said the constitutional phrase should be understood in relation to senators who are able to perform their functions. He argued that the count could exclude senators who have resigned or been expelled, are seriously incapacitated, are outside the country or in hiding, have unknown whereabouts, or are under legal restraint.

Davide also distinguished Avelino v. Cuenco from the present case. He said the 1949 decision did not directly settle an impeachment-vote question because it involved a legislative Senate and a quorum issue. Even so, he said the reasoning could have persuasive value by analogy.

On the question of absentee senator-judges, Davide took the stricter view that a senator who never attended the trial should not be treated as having participated in the court’s work. For senators who attended only part of the proceedings, he left the matter to their conscience and sense of duty, while emphasizing the importance of listening to the witnesses and considering the record.

Panganiban: a fixed 16 could create an unfair result

Panganiban acknowledged that a literal reading of the Constitution could produce a 16-vote requirement. He nevertheless said the circumstances of the case could change the practical denominator. He urged the senator-judges to consider the purpose of the Constitution, fairness, and the need for the impeachment court to function even when some senators cannot participate.

During questioning, Panganiban was asked to consider a situation in which illness, detention, or another legal impediment left only 16 senators able to take part. He said a fixed 16-vote threshold would then require unanimity, which could prevent the Senate from reaching a meaningful decision.

Panganiban also treated the Senate sitting as an impeachment court much like a trial court. In his view, senator-judges should personally hear the evidence and understand the witnesses’ testimony. A senator who deliberately stayed away from the proceedings, he suggested, should not be counted as though that senator had participated in the trial.

Puno: two-thirds is a fraction, not automatically 16

Puno argued that the words “two-thirds” describe a fraction rather than a permanently fixed number. If the Constitution intended to require 16 votes in every situation, he said, it could have stated that number directly.

He favored a contextual and functional reading that would allow the court to account for circumstances legally preventing a senator from acting as a member of the impeachment tribunal. Puno also said Avelino v. Cuenco was not a perfect precedent because it involved a different constitutional provision and a legislative quorum, but its treatment of a senator beyond the chamber’s coercive reach could still serve as one guide.

On absent senator-judges, Puno took a more permissive position than Panganiban and Davide. He said personally seeing a witness is ideal, but a judge may decide from the transcripts, recordings, and other parts of the official record. He also suggested that detained senators could follow the proceedings and receive the transcripts.

Puno further told the court that the Senate, when acting as an impeachment court, has authority to interpret the constitutional language it must apply. The court would not necessarily have to leave every question about the threshold to the Supreme Court.

Azcuna defended counting all 24 senators

Azcuna was the lone dissenter among the four legal advisers on the central denominator question. His position was that “all” means all: as long as senators remain members of the Senate, they should be included in calculating two-thirds. In his view, the threshold should change only if a Senate seat becomes permanently vacant.

Azcuna said the full-membership rule protects an impeached official from being removed by a temporary or partisan majority. He also warned that excluding senators could create opportunities for manipulation if political actors tried to remove potential votes through detention, legal cases, suspension, or other means.

He rejected Avelino v. Cuenco as controlling because that decision involved a different constitutional framework and a legislative quorum rather than an impeachment conviction. On absent senator-judges, Azcuna said the Senate is a tribunal of record. If a senator honestly believes the transcripts and evidence are sufficient to make an impartial decision, Azcuna said that senator should generally be allowed to vote unless the Senate’s rules provide otherwise.

What the disagreement means

The four opinions exposed a clear divide:

• Davide, Panganiban, and Puno viewed the two-thirds requirement as capable of changing with the number of senators legally able to participate.
• Azcuna said all 24 sitting senators should remain the denominator unless a seat is permanently vacant.
• Davide and Panganiban were more skeptical of allowing senators who missed the proceedings to vote.
• Puno and Azcuna said a senator could rely on the official record, even without personally observing every witness.

The disagreement did not resolve the matter. The amici offered legal guidance, but the Senate impeachment court still had to decide whether to uphold, revise, or otherwise address the earlier 16-vote ruling.

The threshold question is important because it could affect the number of votes needed for conviction. It does not determine whether the prosecution has proved the charges under the Articles of Impeachment. A decision on the denominator would be procedural; a verdict would require the court to complete the trial and assess the evidence on the merits.