Vice President Sara Duterte's lawyers on Tuesday defended their use of courtroom objections in the Senate impeachment trial, saying they are dictated by procedural rules rather than litigation strategy after the defense drew attention for repeatedly interrupting prosecutors during earlier hearings.

Defense spokesperson Michael Poa said the legal team objects only when questions are legally improper, rejecting suggestions that the defense was using objections to disrupt proceedings or score tactical advantages.

"It's not a matter of legal strategy. They're under the rules. If a question is objectionable, counsel must object unless we're okay to waive that objection,” Poa told reporters before the fifth day of the Senate impeachment trial.

Last week, defense lawyer Carlo Narvasa raised numerous objections during the prosecution's examination of  NBI agent John Mark Calilung last week, particularly during questioning on Duterte's November 2024.

By contrast, Monday's hearing saw defense lawyer Mark Vinluan raise relatively few objections during the testimony of National Bureau of Investigation (NBI) Regional Director Jeremy Lotoc, one of the prosecution's key witnesses under Article IV of the impeachment complaint.

"Yesterday, we didn't really see any basis to object. You saw that we were reasonable. We weren't objecting," Poa said.

"But if a question is truly objectionable, we will not be doing justice to our client. We will not be doing our jobs if we don't object."

Under the Senate Rules of Procedure on Impeachment Trials, objections must be raised when counsel believes testimony or evidence violates procedural or evidentiary rules. Failure to object may be treated as a waiver, allowing the testimony or evidence to remain on record.

Instead of frequently objecting, the defense devoted much of Monday's cross-examination to challenging the credibility of the NBI investigation, questioning documentary discrepancies and whether investigators acted independently despite the bureau being attached to the Department of Justice.

"It goes into bias basically because then now the report is questionable," Poa said.

He declined, however, to claim that the defense had already established bias.

"But whether we were able to establish bias, once again, is not something for us to say in the media because it would be unfair to the other party," he said.

Still, Poa maintained that the issue was central to the defense's case.

"As to your question, that's why it's important because obviously bias affects everything that goes on in an investigation."

During Monday's cross-examination, the defense suggested that the NBI, an agency under the Department of Justice, could not be viewed as entirely independent because it falls under the executive branch headed by President Marcos, one of the alleged victims in the case. 

Lotoc rejected the claim, testifying that investigators acted independently and based their findings solely on evidence.

The prosecution is using the NBI investigation to support Article IV of the impeachment complaint, which accuses Duterte of her alleged threats against Marcos, the First Lady and Romualdez. 

Duterte has denied making an actionable death threat, arguing that her remarks have been taken out of context.