The Senate majority bloc rejected a proposal by opposition senators to ask the Sandiganbayan to allow their detained colleagues to attend the impeachment trial, even as Sen. Ping Lacson said Sunday that their absence could effectively work in favor of Vice President Sara Duterte's acquittal.

The proposal was first raised during the all-senators caucus on 3 June, three days before the formal start of the impeachment trial.

According to Lacson, Sen. Loren Legarda presented a draft letter requesting the Sandiganbayan to allow Sen. Jinggoy Estrada, who is detained on plunder charges, to participate in the proceedings.

Lacson said nearly all members of the 11-member minority bloc signed the proposed letter.

He said the majority did not object to the proposal itself but refused to sign it, arguing that the Senate should not interfere with the jurisdiction of a co-equal court.

Only Estrada's lawyers, Lacson said, have the legal standing to seek such relief.

"Let the Sandiganbayan make the ruling without the intervention or any comment from the impeachment court or the senators," Lacson said in Filipino during a radio interview.

Lacson said only Legarda and Sen. Robin Padilla from the majority attended the closed-door meeting. At the time, Sen. Rodante Marcoleta had yet to be arrested on separate plunder charges.

Senate Minority Leader Alan Peter Cayetano later indicated he would formally raise the proposal before the impeachment court. Lacson, however, said the measure had little chance of securing majority support.

Last week, the Sandiganbayan denied Estrada's motion to attend the impeachment trial, citing a lack of merit. The anti-graft court also noted the senator's 90-day preventive suspension, which bars him from performing official duties while facing plunder and graft charges linked to alleged flood control kickbacks.

Lacson said the majority supports full participation by all senator-judges to avoid questions over the 16-vote conviction threshold, but stressed that such concerns should not come at the expense of judicial independence.

"If the impeachment court were to ask for a comment, our position would simply be not to comment," he said.

He also expressed hope that legal questions surrounding the conviction threshold would be resolved early in the proceedings to avoid delays or challenges to the trial's validity.

Lacson noted that impeachment decisions are final and cannot be appealed under the Constitution.

He added that the impeachment court itself should neither initiate a petition nor ask the prosecution to elevate the issue to the Supreme Court to preserve the tribunal's impartiality.

Senate President Sherwin Gatchalian and impeachment court presiding officer Senate President Francis "Chiz" Escudero have both maintained that 16 votes are required for conviction, regardless of how many senator-judges are present.

Under that interpretation, absent senators would simply be recorded as abstaining, reducing the number of votes available for conviction and effectively benefiting the respondent.