September 16, 2026

The Court enlisted retired Chief Justice Hilario G. Davide Jr., who submitted a written memorandum; retired Chief Justice Artemio V. Panganiban; retired Chief Justice Reynato S. Puno; and retired Associate Justice Adolfo S. Azcuna. It asked them whether 'all the members of the Senate' means the full 24-member Senate or only senators legally and physically able to participate and vote; whether Avelino v. Cuenco bears on unavailable senators; and whether a senator-judge who did not substantially participate may vote on the final question.

Davide's memorandum said the constitutional framers had presumed that 'members' excluded people unable to exercise senatorial powers because of mental, physical, health, or legal restraints. It therefore urged a denominator of senators qualified to vote and treated Avelino v. Cuenco as not directly controlling in impeachment but potentially useful by analogy. For senators who had not substantially participated, the memorandum left the matter to their conscience and sense of duty.

Panganiban described impeachment as sui generis, with legal and political characteristics. He argued that senators should be guided by truth and fairness, test documents and witness testimony firsthand, hear both sides before judgment, and independently evaluate the evidence. On the threshold, he favored counting senators able to vote; on review, he said Supreme Court intervention would require grave abuse of discretion.

Puno framed the wording as supporting more than one school of constitutional interpretation and argued for a contextual rather than purely literal approach. He described ordinary Senate impeachment actions as political questions, while identifying a narrower justiciable category when a respondent's right to a fair and impartial tribunal is violated. On detained participation, he raised an open question whether courts and the Senate could reconcile their jurisdictions by allowing a detained senator-judge to perform that temporary judicial duty, potentially including remote participation.

Azcuna argued from the constitutional history of the supermajority requirement that it was designed to make conviction difficult. In his view, the denominator consists of all existing senators rather than those present: a senator may be unable to vote yet still count unless dead, resigned, or removed. He said making the threshold variable could permit manipulation by lowering it when senators are prevented from participating.

Fr. Ranhilio C. Aquino submitted a memorandum of law for the Court's record. The Chair confirmed that it had already been furnished to the parties and senator-judges and uploaded to the Senate website.

After 17 senator-judges were reported present and a quorum declared, the Chair recognized the duly elected Presiding Officer to preside over the Impeachment Court.

The Chair said the day would hear friends of the Court rather than hold a trial, and identified questions concerning the two-thirds denominator, unavailable senator-judges, and participation in a final vote.

Before the oral consultations, the Chair directed the Clerk to read a synopsis of retired Chief Justice Hilario Davide Jr.'s written memorandum, which had been distributed and posted.

After the amici consultation, the Chair moved to administrative matters and adjourned the Court until Monday, September 21, at 10 a.m.

The Chair directed the Clerk to serve show-cause orders on certain House prosecution-panel members after trial, pursuant to the Court's prior sub judice directive.

The Chair granted subpoenas for Attorney Ariel Ronquillo and Rendell Sopena for September 21 through 23, and set September 23 subpoenas for Mayor Sebastian Duterte, Attorney Gary Samonte, and Police Major Jerickson Sangalang subject to a September 22 assessment of whether they would instead be reset.

The Chair said the Court would identify exhibits common to the parties that had been pre-marked during the pretrial conference, to abbreviate the Court's time.

Responding to defense counsel's request for clarification, the Chair said the parties were free to use their September 23 oral-argument time on matters beyond the three issues previously identified.

Sen. Juan Miguel "Migz" F. Zubiri invoked Senate Rule 135 and a 2001 treaty vote to ask whether 13 votes could lawfully count as two-thirds of a 20-member Senate. Four treaties had passed after vacancies and an official mission abroad reduced those able to vote. Chief Justice Artemio V. Panganiban said the Senate had not violated the Constitution: 13 was two-thirds of 20. He distinguished treaty concurrence, a deliberative proceeding, from an impeachment trial, but agreed that former senators and those unable to vote were excluded.

Sen. Joel Villanueva asked whether Article XI's two-thirds-of-all-members clause fixes the denominator at 24 despite a senator's detention or absence. Chief Justice Reynato S. Puno said the wording permits competing readings and left court-authorized temporary or remote participation unresolved. Chief Justice Artemio V. Panganiban said detention preserves membership but a trial judge should observe evidence firsthand; Justice Adolfo S. Azcuna said voting is separate from a denominator that changes only on death, resignation, or removal. Villanueva then asked how to avert both an absence-based veto and engineered exclusion. Azcuna proposed legislation to enable detained senators to participate, while Panganiban stressed justice for the public and Puno the respondent's right to an impartial tribunal.

Sen. Erwin Tulfo tested the threshold dispute from its design to its consequences: why Philippine framers chose two-thirds of all senators rather than the U.S. rule based on those present, and whether a fixed 16 should remain when detention, illness or another absence makes a decision impossible. Justice Adolfo S. Azcuna said the all-members formula deliberately makes conviction harder and counts every senator until death, resignation or removal; Chief Justice Artemio V. Panganiban said senators able to vote should not be immobilized. Tulfo then pressed literal versus contextual reading and institutional authority. Chief Justice Reynato S. Puno favored reading the clause with the respondent's right to a fair and impartial tribunal, calling ordinary impeachment decisions political but due-process violations reviewable. Panganiban said the Senate decides, subject to Supreme Court review only for grave abuse; Azcuna said the Supreme Court ultimately decides whether the Senate's interpretation complies with the Constitution.

Sen. Vicente C. Sotto III announced the Senate's receipt of Fr. Ranhilio C. Aquino's voluntary memorandum of law and proposed entering it into the Impeachment Court record. The Chair said it had already ordered the Clerk to furnish it to the parties and senator-judges and post it on the Senate website; Sotto accepted the response.

Sen. Panfilo M. Lacson asked whether consulting the former justices would help protect the Impeachment Court against a later grave-abuse-of-discretion charge; Chief Justice Artemio V. Panganiban called the step prudent. Lacson then tested the threshold with nine senators stranded abroad, leaving 15 available. Justice Adolfo S. Azcuna said a fixed 24-member denominator would require acquittal because 16 votes could not be reached; Panganiban said two-thirds of the 15 could still render justice. Lacson warned that the framers may not have anticipated widespread involuntary absence and that a rigid threshold could leave Filipinos without accountability. He then asked when the Court's interpretation becomes justiciable. Panganiban said the Senate's judgment controls unless its decision amounts to arbitrary, capricious grave abuse of discretion, not simply a view the Supreme Court rejects.

Sen. Francis Pangilinan asked whether revisiting the Presiding Officer's 16-vote threshold during the proceeding—particularly by adopting a lower threshold—would change the rules midstream and deny the respondent due process. Chief Justice Artemio V. Panganiban said no violation had yet occurred because the Senate had neither voted nor implemented a change. Chief Justice Reynato S. Puno said the Court was interpreting an unsettled provision with several reasonable readings, not changing an established rule; without a final Senate interpretation or demonstrated injury, a court challenge would be premature. Justice Adolfo S. Azcuna agreed, calling the threshold interpretation procedural and applicable to the pending trial without impairing a vested right.

Sen. Risa Hontiveros tested how absences affect the two-thirds denominator. Chief Justice Artemio V. Panganiban said a senator unable to hear evidence should neither vote nor count; Chief Justice Reynato S. Puno said a sworn absent senator's status depends on whether the Impeachment Court could compel participation, while a no-oath case turns on reason, stage, and the oath's role. Her scenario of a president baselessly detaining 10 senators to block 16 votes drew Justice Adolfo S. Azcuna's acceptance of a fixed count's occasional accountability risk rather than a manipulable lower threshold that could make conviction too easy. On why impeachment lies with the Senate, Panganiban cited senators' national electoral mandate for political judgment; Azcuna called it a legislative check.

Sen. Robinhood "Robin" Padilla began with truth and fairness for the Impeachment Court's own members, a premise Chief Justice Artemio V. Panganiban endorsed, then tested the Court's independence against the Sandiganbayan's custody of senator-judges. Chief Justice Reynato S. Puno said the courts' jurisdictions must be reconciled, suggesting limited temporary liberty, potentially with online participation, for a detained senator to sit as a judge. Padilla carried that participation concern into the practical and constitutional questions: whether senator-judges returning after more than 20 trial days could rely on recordings, and whether "all members" could be interpreted differently or changed when the Constitution was ratified by plebiscite. Justice Adolfo S. Azcuna said the current rules require physical presence and bar remote participation or voting, although rules or a statute could change; detained senators still count in the denominator. He distinguished a constitutional amendment, requiring the constitutional process and a plebiscite, from Senate interpretation, and Puno confirmed the amendment routes. Padilla ultimately urged the Court to change its attendance rules before voting on the threshold.

Senate President Sherwin T. Gatchalian asked whether the Senate Impeachment Court alone may interpret Article XI, Section 3(6), and whether the two-thirds denominator is a political question. Chief Justice Reynato S. Puno said the Court's authority was exclusive and the membership issue generally political, though an outcome denying the respondent fair and impartial judges could be reviewed for due process. On participation, Chief Justice Artemio V. Panganiban said a senator unable to learn the truth and render a fair judgment should not vote; Justice Adolfo S. Azcuna said omitting a still-serving nonparticipant from the denominator could invalidate a conviction. Gatchalian then asked why the threshold demanded contextual rather than literal reading and whether the Court could alter the Presiding Officer's ruling. Puno said the consultation reflected a contested text: literal reading fits only clear language; competing readings, especially where rights are affected, require context. Panganiban said a quorum majority could modify or reverse a temporary ruling before final judgment.

Sen. Pia S. Cayetano tied the threshold debate to what she described as pressure on senator-judges: two detained colleagues, one hiding after an asserted ICC-warrant threat, one on medical leave facing possible plunder cases, and NBI comments about her Singapore trip. Fearing for her liberty and right to speak, she argued that retaining the threshold would let senator-judges continue speaking in Court. Cayetano asked Chief Justice Reynato S. Puno whether unjustifiably barring a senator-judge from participating and denying the respondent due process were justiciable; he said both involved specific rights, judicial standards and remedies. Invoking People v. Gray, she asked Justice Adolfo S. Azcuna whether political pressure that could keep senators from attending was why the threshold should stay unchanged. Azcuna declined to assess the cases but said it guards against artificial, partisan moves that prevent justice.

Defense counsel Michael Poa placed on record that the defense's participation in the amici proceeding and later oral arguments would be ad cautelam because the proceedings could affect the respondent's rights.

For the next witness sequence, prosecution counsel corrected its earlier presentation and said it would call Attorney Ariel G. Ronquillo of the Civil Service Commission first, followed by Attorney Gerardo F. Del Rosario of the Securities and Exchange Commission and Rendell P. Sopena of the Philippine Government Electronic Procurement System Office of the DBM.

Panganiban on judicial review: "Not just ordinary abuse of discretion, but grave abuse of discretion."

Puno characterized the interpretive debate: "There is no correct or wrong Decision on these issues. There is only a preferred decision."

Azcuna on a flexible denominator: "That is the trade-off"with 16 participating senators, he said, "about 10 is enough to convict a president. So that's too small a majority."

The Court did not announce a resolution of its three questions before moving to administrative matters and adjourning: the meaning of 'all the members,' treatment of unavailable senator-judges, and a nonparticipating senator-judge's ability to vote on the final question.

Whether the September 23 subpoenas for Mayor Duterte, Samonte, and Sangalang would remain in place was left for the Chair's September 22 assessment of the witness schedule.