MANILA, Philippines — The Senate impeachment court is turning to four retired Supreme Court justices to settle a question that could decide Vice President Sara Duterte’s fate: Does it still take 16 votes to convict when four senator-judges are not taking part in the trial? The impeachment court on Thursday named retired Chief Justices Artemio Panganiban, Reynato Puno and Hilario Davide Jr., and retired Associate Justice Adolfo Azcuna as amici curiae, or legal advisers to the court, on the potentially decisive voting issue. Panganiban (who writes a column, “With Due Respect,” in the Inquirer), Puno and Azcuna will appear before the impeachment court on Sept. 16. Davide will submit a legal memorandum that will become part of the record, according to impeachment court spokesperson Reginald Tongol. READ: Barbers: Expert views on VP Duterte voting needed before taking issue to SC “The impeachment court is not leaving constitutional math to guesswork or chance,” Tongol said, adding that the four legal luminaries were tapped to provide guidance on the contentious issue. Their intervention came after Senator-judge Erwin Tulfo on Tuesday asked presiding officer Francis “Chiz” Escudero to revisit his July 6 ruling that 16 votes would be needed to convict an impeachable official. “When we refer to all members, who exactly are we counting?” Tulfo had asked. Article XI, Section 3(6) of the 1987 Constitution provides that an impeached official cannot be convicted “without the concurrence of two-thirds of all the members of the Senate.” The dispute centers on whether “all members” should mean all 24 senators regardless of their ability to participate, or only those legally able to take part in the impeachment proceedings and final vote. Four senators are currently unable to attend the trial: Ronald “Bato” dela Rosa, who is in hiding amid an International Criminal Court arrest warrant; Jinggoy Estrada and Rodante Marcoleta, who are facing nonbailable plunder charges before the Sandiganbayan; and Loren Legarda, who is reportedly in France on an extended medical leave since Aug. 3. Estrada, Marcoleta and Dela Rosa have not attended a single impeachment trial. Their absence prompts the question of whether the 16-vote requirement should remain despite the reduced number of participating senator-judges. What conviction means If Duterte is convicted by the Senate acting as an impeachment court, she will immediately lose her position as Vice President. The impeachment court may impose an additional penalty of perpetual disqualification from holding any public office, permanently barring her from running for government positions or public service in the future. A conviction does not preclude separate criminal or civil proceedings, meaning she can still face trial in regular courts for civil and criminal liabilities. The three retired justices who will appear on Sept. 16 are expected to present their legal views and answer questions from the senator-judges. The prosecution and defense panels will present their own oral arguments on Sept. 23, with each side given 15 minutes. The senator-judges are then expected to vote on whether to overturn Escudero’s ruling on the threshold. Tongol said the amici curiae would not be cross-examined because they would provide legal doctrine, not factual evidence. The prosecution and defense panels would only listen to their presentations.

“Since an amicus curiae provides legal doctrine, not factual evidence and the constitutional right to cross-examine applies only to fact witnesses, not scholars advising the bench, the legal panels will just sit and listen during the whole presentation,” Tongol said. READ: Senate impeachment court revisiting ‘2/3’ conviction rule The four advisers bring extensive constitutional and judicial experience to an issue that could affect the outcome of the impeachment trial. Panganiban and Puno both served as chief justice of the Supreme Court. Puno was later appointed chair of the Consultative Committee that reviewed the 1987 Constitution under President Rodrigo Duterte. Davide was among the 50 members of the 1986 Constitutional Commission that drafted the 1987 Constitution. He later chaired the Commission on Elections and joined the Supreme Court in 1991. Then President Joseph Estrada appointed Davide chief justice in 1998, making him the presiding officer of Estrada’s impeachment trial. Azcuna was also a member of the Constitutional Commission. He later served as presidential legal counsel and spokesperson to then President Corazon Aquino before being appointed to the Supreme Court as an associate justice by President Gloria Macapagal-Arroyo in 2002. While the impeachment court tackles the voting issue, the prosecution is preparing to open Article 2, which accuses Duterte of having unexplained wealth. Bicol Saro Rep. Terry Ridon said on Thursday that the prosecution had asked the court to subpoena three witnesses: retired Sandiganbayan Presiding Justice Amparo Cabotaje-Tang, Karen Batu, officer in charge of the Office of the Ombudsman Records Division, and Gerardo del Rosario, director of the Securities and Exchange Commission’s (SEC) Company Registration and Monitoring Department. Cabotaje-Tang is expected to testify on public accountability and integrity in public office, including mechanisms for addressing undisclosed or unexplained wealth and prohibited business interests. Batu will testify on Duterte’s statements of assets, liabilities and net worth, or SALNs, particularly those she submitted to the Ombudsman. Del Rosario will authenticate and identify SEC records involving companies registered in Duterte’s name. Target timeline The three witnesses are expected to lay the legal and documentary groundwork for the prosecution’s case involving Duterte’s alleged unexplained wealth and business interests. Ridon said the prosecution hoped to open and finish Article 2 within two to three weeks, depending on the length of the hearings. Batu and the SEC officials earlier testified before the House justice committee when it heard the impeachment complaints against Duterte. Cabotaje-Tang retired from the Sandiganbayan in November 2024 upon turning 70. President Benigno Aquino III appointed her presiding justice in October 2013. Before joining the anti-graft court, she served at the Office of the Solicitor General, eventually becoming assistant solicitor general. She represented the government before the Sandiganbayan, including in efforts to block a plea-bargaining agreement with former military comptroller Carlos Garcia. /das