MANILA – The Senate Impeachment Court has secured the participation of four retired Supreme Court justices as amici curiae to provide legal guidance on the constitutional vote threshold being challenged in an appeal filed by Senator-Judge Erwin Tulfo.

Senate Impeachment Court spokesperson Atty. Regie Tongol said Thursday the Office of the Clerk of Court had begun issuing and serving the orders for the appointment of the amici curiae in compliance with the directives of Presiding Officer Senate President Francis “Chiz” Escudero.

The four legal experts are Chief Justice Artemio V. Panganiban (Ret.), Chief Justice Reynato S. Puno (Ret.), Supreme Court Associate Justice Adolf S. Azuna (Ret.), and former Chief Justice Hilario G. Davide Jr. (Ret.).

Panganiban, Puno, and Azuna are set to physically appear before the Senate on Sept. 16, 2026, to present their expert advisories.

Davide, who served as presiding officer during the impeachment trial of former President Joseph Estrada, will instead submit a legal memorandum, according to the court.

Tongol said the court may invite additional experts if necessary, noting that the four-member roster represents its list of amici curiae thus far.

“The Impeachment Court is not leaving constitutional math to guesswork or chance,” Tongol said.

The court said the participation of the retired justices is intended to ensure that proceedings on the constitutional issue are grounded on established legal doctrine.

Any written advisories submitted before the Sept. 16 presentation will first be made available to the Senator-Judges for review. The court said it will not release or comment on their substantive contents before their formal presentation.

During the Sept. 16 proceedings, the three physically appearing amici curiae will present their advisories, while Davide’s memorandum will be formally entered into the record.

The Senator-Judges will then be given the opportunity to ask clarificatory questions.

The court said the House Prosecution Panel and the respondent’s counsel will not participate in the questioning, explaining that an amicus curiae provides expert legal doctrine rather than factual evidence and that the constitutional right to cross-examine applies to fact witnesses, not legal scholars advising the bench.

Floor time for the proceedings will be strictly controlled by the Presiding Officer.

The impeachment court will then hear oral arguments from the trial teams on Sept. 23, with the House Prosecution Panel and the respondent’s counsel each allotted 15 minutes.

After a final round of questions from the Senator-Judges, the court will divide the house and proceed to a vote on the appeal, with time allotted for the Senator-Judges to explain their respective votes.

Tongol said the impeachment court would not rush the resolution of the constitutional threshold issue.

“Doctrinal accuracy and constitutional exactitude take precedence over speed,” he said.