Duterte Impeachment Trial: Defense Questions Credibility as Key Witness Testifies

Duterte Impeachment Trial: Defense Questions Credibility as Key Witness Testifies

By Bing Jabadan – TheNATIONWEEK.com | July 9, 2026

MANILA, Philippines – The impeachment trial of Vice President Sara Duterte concluded its first week with intense focus on the prosecution’s initial witness and significant procedural developments. The Senate impeachment court has compelled the appearance of Office of the Vice President Chief of Staff Undersecretary Zuleika Lopez, while the defense launched a robust challenge to the credibility of the prosecution’s testimony.

Undersecretary Lopez is scheduled to testify on Monday, July 13, as a pivotal witness for the prosecution. She is one of three individuals the prosecution plans to call in the second week to substantiate Article IV, the “grave threats” charge. This article alleges that Duterte orchestrated a plot to harm President Ferdinand Marcos Jr., First Lady Liza Araneta-Marcos, and former House Speaker Martin Romualdez. Also slated for testimony are NBI lawyer Jeremy Lotoc and House Sergeant-at-Arms Capt. Belinda Bello. An early adjournment of the first week allowed the prosecution to re-strategize, advancing Lotoc’s testimony to the upcoming Monday session.

The day’s proceedings were dominated by the cross-examination of the prosecution’s first witness, NBI Senior Agent John Mark Calilung. Calilung testified that the NBI initiated its investigation into Duterte’s alleged threats based on its mandate to probe threats against high-ranking officials, even without a formal complaint from the purported victims.

The defense team, led by lawyer Carlo Joaquin Narvasa, meticulously questioned Calilung’s credentials, specialized training, and whether the NBI’s investigation was launched independently (motu proprio) or at the behest of higher authorities. Senator-judges also scrutinized Calilung’s investigative methodologies and qualifications, aiming to establish the thoroughness and impartiality of the NBI’s actions.

A notable exchange occurred when Senator-Judge Risa Hontiveros challenged defense counsel Narvasa on the relevance of video clips depicting Lopez crying during her detention by the House in November 2024. Hontiveros questioned whether the defense intended to argue that Duterte’s alleged threats were justified due to the perceived oppression of her chief of staff. Narvasa confirmed the defense’s position, asserting a systematic campaign of oppression by the House of Representatives. Presiding Officer Sen. Francis Escudero also allowed the defense to comment on a prosecution remark regarding whether Duterte’s statements in the “kill-threat” video constituted an impeachable offense.

In a related development, the prosecution filed a motion for a subpoena duces tecum and ad testificandum for a sealed Bureau of Internal Revenue (BIR) box containing Duterte’s tax records. This follows the court’s earlier return of the box to the BIR due to a lack of formal directive. Prosecution lawyer Benjamin Tolosa Jr. indicated that seeking President Marcos’ authorization to open the tax documents, a precedent from the Corona impeachment trial, remains a viable option. Tolosa reiterated the prosecution’s focus on constructing an “airtight case” and stated that efforts to lower the two-thirds conviction threshold are not a current priority.

Meanwhile, public attention remains fixed on the proceedings, with many Filipinos observing for potential biases among Senator-judges, especially in light of a Supreme Court petition challenging the legitimacy of the trial.

Malacañang expressed support for Senator Escudero’s election as presiding officer amidst a Supreme Court petition filed by Duterte-allied lawyer Israelito Torreon and others, seeking a temporary restraining order against the trial. Duterte’s own defense counsel denied any knowledge of the Torreon-led petition. Palace Press Officer Claire Castro affirmed President Marcos’ support for the Senate’s actions, provided they remain within legal bounds. Castro further suggested that Vice President Duterte should personally address the charges rather than relying solely on legal technicalities for her defense.

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