The required threshold to convict Vice President Sara Duterte remains fixed at 16 votes, or two-thirds of all Senate members, despite the persistent bickering between the two rival camps in the chamber over quorum-related issues.

Acting Senate President Win Gatchalian said the constitutionally mandated threshold would be strictly adhered to during the VP’s trial at the Senate impeachment court scheduled to begin on 6 July.

This contradicted the allegation of his predecessor, Senator Alan Cayetano, that the Gatchalian faction’s insistence on a leadership revamp on 3 June with only a 12-member quorum could also lower the threshold for a conviction in an impeachment trial.

“The rules are clear. And the constitutional threshold — 16 votes — will be faithfully observed,” Gatchalian said. “Our duty is to follow the Constitution, and that is what we will do.”

Article XI, Section 3(6) of the Constitution sets the required number of votes to convict a high-ranking official at 16, which is equivalent to two-thirds of the 24-member Senate.

A conviction carries a penalty of removal from office and perpetual disqualification from holding further office. This could derail Duterte’s presidential bid in 2028.

Gatchalian said the internal dispute over the quorum will not affect the impending impeachment trial and the threshold will remain at 16, regardless of how many senators attend the trial.

In May, Cayetano and his allies attempted to amend the Senate rules to allow senators — for justifiable reasons — to participate in sessions and cast their votes remotely.

However, the move was met with fierce objections from the Gatchalian bloc, which accused the Cayetano faction of railroading the process ahead of the arrest of Senators Jinggoy Estrada and Ronald dela Rosa, thereby allowing them to vote in the impeachment trial even if they were detained or in hiding.

Earlier, former Senate president Franklin Drilon speculated that the move may have been intended to outnumber and defeat the Gatchalian bloc should Vice President Duterte’s bank records be subpoenaed in connection with the allegations of graft and corruption against her.

Cayetano’s bloc, composed mostly of senators allied with Duterte, denounced the leadership change on 3 June, deriding it as unconstitutional for lacking one vote to meet the 13-member majority threshold to conduct business and elect a new Senate president and other officers.

Gatchalian and his allies, however, countered that the 12-member quorum was based on previous Senate precedents, including the landmark 1949 Supreme Court case of Avelino v Cuenco, which made it legal.

The jurisprudence allowed the adjustment of the base number of senators when certain members were legally beyond the Senate’s coercive reach.

Because of this, the Gatchalian-led faction insisted the simple majority was now 12 since the base number had dropped from 24 to 22 following the arrest of Estrada and the continued absence of Dela Rosa, who were in Cayetano’s bloc.

Reports indicate that Senator Francis “Chiz” Escudero, a lawyer like Cayetano, is being eyed by Gatchalian’s faction to be the presiding officer of the impeachment trial.

The pre-trial conference for Duterte’s impeachment case is scheduled for 18 June, with both her defense team and the House prosecution panel directed to submit their pre-trial briefs by 15 June.