MANILA – Three retired Supreme Court justices will appear before the Senate impeachment court on Wednesday to address whether 16 votes should remain the threshold for convicting Vice President Sara Duterte.

Presiding Officer Sen. Francis “Chiz” Escudero said Monday that retired Chief Justices Artemio Panganiban and Reynato Puno, along with retired Associate Justice Adolfo Azcuna, will participate as amici curiae, or friends of the court, during the Sept. 16 proceedings.

The three legal experts were invited to help the impeachment tribunal resolve the interpretation of the constitutional requirement that an impeachment conviction must secure the support of two-thirds of all Senate members.

“For the information of the parties and the public, the court formally announces that, as discussed during the trial of Sept. 10, 2026, it has secured the participation of the following legal luminaries as amici curiae on the meaning of all members under Article 11, Section 3-6 of the Constitution, as raised by Senator-Judge Erwin Tulfo,” Escudero said.

The issue centers on Article XI, Section 3(6) of the 1987 Constitution, which states that an impeachment conviction requires the concurrence of “two-thirds of all the Members of the Senate.”

The Senate is constitutionally composed of 24 members, making two-thirds equivalent to 16 votes.

The appearance of the retired justices comes as the impeachment court considers the proper interpretation of “all the Members of the Senate” and whether the 16-vote threshold applies under the circumstances of Duterte’s impeachment trial.