Full: Amici Curiae Oral arguments | Day 26 of the senate impeachment trial of VP Sara Duterte

Summary

The Senate impeachment court heard invited amici curiae on three questions: how to calculate the constitutional two-thirds vote required for conviction; whether Avelino v. Cuenco guides that calculation; and whether senators who missed or took little part in the hearings may still vote.

Before the presentations, defense counsel Michael Pua said the defense was participating at cautelam—with caution—because the proceedings could affect its client’s rights. The court also read a synopsis of former Chief Justice Hilario Davide Jr.’s memorandum. Davide was absent because of a recent medical procedure.

Positions of the amici curiae

Hilario Davide Jr.

In a memorandum read in his absence, Davide argued that “all members” should mean senators legally and physically capable of performing their duties, rather than automatically all 24 seats. Senators who have resigned or been expelled, are incapacitated, or are legally unable to participate—including those in custody or outside the country—should not count toward the denominator.

He said Avelino v. Cuenco is not directly controlling because it concerned a Senate quorum, though it may offer guidance by analogy. A senator who never attended or performed any duties could be treated as unable to participate; whether limited participation is enough should be left to the senator’s conscience. But simply not questioning witnesses does not prove nonparticipation.

Artemio Panganiban

Panganiban described impeachment as both a legal process and a political one, and said senators serve as elected representatives rather than as ordinary judges or legal scholars. Although two-thirds of 24 is 16, he argued that constitutional interpretation should consider purpose and real-world circumstances, not abstract arithmetic alone.

Senators should decide according to truth and justice, actively assess the evidence, and ensure the parties have a fair opportunity to be heard. He questioned whether it would be fair for absent or legally impeded senators to vote. He said the Senate’s decision is final except where the Senate commits grave abuse of discretion.

Reynato Puno

Puno argued that the impeachment court itself has authority to interpret the constitutional voting rule because the Senate has the exclusive power to try and decide impeachment cases. He favored a contextual and functional reading over a strictly literal one, allowing the Senate to consider whether legal incapacity affects who counts as a member for the threshold.

He said Avelino v. Cuenco is not a direct precedent but may be a useful guide. On attendance, he noted that judges can sometimes decide cases using transcripts and records rather than having personally heard every witness. However, he warned that denying a senator the right to sit, or denying the accused a fair and impartial tribunal, could violate due process and lead to Supreme Court review.

Adolfo Azcuna

Azcuna took the opposing view on the denominator: “all members” means all 24 senators, so the two-thirds requirement remains fixed at 16. He said the higher threshold is intended to prevent a temporary political majority from removing an elected official without broad support.

He considered Avelino v. Cuenco inapplicable because it dealt with different constitutional wording and a quorum, not conviction in an impeachment trial. As for senators who missed hearings, he viewed the matter as an internal Senate question and said he would generally allow a senator to vote if, after reviewing the record, the senator could honestly reach an impartial decision.

The presentations revealed disagreement over whether the two-thirds threshold should be fixed at 16 or adjusted for senators unable to participate. The amici also differed on how much participation is necessary, while several emphasized the importance of the trial record, fairness, and senators’ own judgment.

Presenters and contributors

• Hilario Davide Jr. — former Chief Justice; memorandum synopsis read in his absence
• Artemio Panganiban — former Chief Justice; amicus curiae
• Reynato Puno — former Chief Justice; amicus curiae
• Adolfo Azcuna — former Associate Justice; amicus curiae
• Michael Pua — defense counsel; brief statement on the record
• Court clerk — read Davide’s memorandum synopsis