A dispute emerged in the Senate on Monday over who should preside over the impeachment trial of Vice President Sara Duterte, after Sen. Francis “Chiz” Escudero was elected presiding officer by a 12-8 vote.

Despite the outcome, Sen. Alan Peter Cayetano urged colleagues to adhere to existing impeachment rules, insisting that the Senate president should lead the proceedings to ensure fairness and due process.

“I thought that’s why we have rules — it dictates fair play. And the rule says it is the Senate president who will preside,” Cayetano said. “So now, if we’re not going to follow the rules, what are we talking about in terms of fairness and due process?”

Cayetano said deviating from prescribed rules could raise questions about the integrity of the trial and the Senate’s commitment to impartiality.

Sen. Pia Cayetano echoed the call, stressing the need to follow the Constitution. She urged fellow senator-judges to review provisions governing impeachment trials, which she said indicate that the Senate president should preside.

She also suggested convening a session to amend impeachment rules if needed, including provisions on the presiding officer.

“We have to call a regular session to amend the impeachment rule, edi tawagin niyo yung Malacañang,” she said.

"Nagpa-special session naman po siya 'di ba?" Cayetano added, referring to the possibility of requesting the executive to convene a special session, similar to the joint session held on June 17 upon the proclamation of President Ferdinand Marcos Jr.

However, Sen. Francis “Kiko” Pangilinan disputed the Cayetanos’ interpretation, saying the Constitution does not explicitly require the Senate president to preside over impeachment trials.

“The Constitution does not provide that the Senate president must preside in cases of impeachment trial,” Pangilinan said.

The Senate convened as an impeachment court on Monday, July 6, marking the first day of the 92-day trial against Duterte.