Senator Francis "Kiko" Pangilinan is the most qualified to serve as the presiding officer of Vice President Sara Duterte's impeachment trial, according to human rights advocate and public interest lawyer Antonio Audie Bucoy, citing his legal background, experience, and reputation for impartiality.

Speaking in a radio interview, Bucoy said the presiding officer wields significant authority over the conduct of an impeachment trial, making his legal competence and neutrality essential.

"The presiding officer has broad powers," Bucoy said. "He orders the issuance of writs, summonses and subpoenas. He regulates the courtroom and rules on procedural questions, including whether the evidence is competent, material and relevant."

Under the Senate impeachment rules, the presiding officer also decides procedural matters, enforces time limits, and serves as the channel through which senator-judges may ask question witnesses.

Unlike regular court proceedings, senators in an impeachment trial are not allowed to directly question the witnesses. Instead, they must submit their written questions to the presiding officer, who will determine if they are proper before they could be asked in open court.

"In other words, the presiding officer filters the questions," Bucoy said.

Although the Senate can overturn rulings made by the presiding officer through a vote, Bucoy said the position is crucial because the presiding officer guides the overall flow of the proceedings.

"He is the one steering the entire process," he said.

Bucoy said Pangilinan was a stronger candidate than the others being floated because of his legal training and previous experience as a senator-judge during the impeachment trial of former Chief Justice Renato Corona.

"He studied law at the University of the Philippines College of Law," Bucoy said. "He has a clear advocacy for clean governance, and throughout his years in the Senate, he has not been tainted by corruption scandals."

He added that impartiality is just as important as legal expertise.

"The most important thing is impartiality," Bucoy said. "You should not only be impartial, but you must also appear impartial."

Bucoy contrasted Pangilinan with Senator Francis "Chiz" Escudero, whose possible role as presiding officer has drawn criticism from some sectors because of the corruption allegations raised against him and the statements he made criticizing the impeachment process.

Bucoy said those issues could raise concerns about his neutrality. He clarified, however, that any pending complaints against Escudero would have no legal bearing on his ability to preside over the impeachment trial.

"They have nothing to do with the impeachment proceedings," Bucoy said.

The lawyer also noted that the Senate's amended impeachment rules now allow the senators to elect a presiding officer instead of automatically assigning the role to the Senate president.

"They can nominate and they can choose," Bucoy said, adding that the amendment appears intended to give senators greater flexibility in selecting someone with the appropriate legal background.

He said only a few incumbent senators possess both the legal training and experience to preside over an impeachment proceeding, describing the role as highly technical.

"Being a presiding officer is technical," Bucoy said. "You need legal training."

The Senate is expected to decide who will preside over the proceedings under the chamber’s revised impeachment rules.