The camp of Vice President Sara Duterte is weighing a Supreme Court (SC) challenge to the Senate impeachment court’s new voting formula, which her spokesperson Atty. Salvador Paolo Panelo Jr. said violates the Constitution by effectively changing the basis for the two-thirds vote required to convict an impeached official.

Panelo said Thursday the Constitution expressly requires the concurrence of two-thirds of all members of the Senate for an impeachment conviction, and argued that the Senate impeachment court had no authority to replace the previously fixed 16-vote threshold with a formula that excludes senators who cannot participate in the proceedings.

“Malinaw itong paglabag sa Saligang Batas dahil ang sinasabi ng Saligang Batas ay two-thirds of all members ng Senado ang kinakailangan for conviction at binago nila ito kahapon,” Panelo said in a television interview.

The Senate impeachment court on Wednesday voted 13-1, with six senator-judges not participating, to overturn its earlier interpretation that 16 votes were required to convict Duterte.

Under the new ruling, the two-thirds requirement will be computed based only on senators who are “legally and factually capable of participating” when judgment is rendered. Senators who are detained, suspended, medically or physically incapacitated, beyond the Senate’s coercive processes or otherwise similarly situated may be excluded from the voting base. 

The ruling did not set a new fixed number of votes. Instead, the court will first determine which senators remain legally and factually capable of participating before computing the two-thirds requirement. Any resulting fraction will be rounded up. 

But Panelo said the Senate impeachment court cannot alter what he described as an explicit constitutional requirement.

“Ang Senado has no power to do this, kaya grave abuse of discretion ito,” he said.

He said the defense could ask the SC to nullify the ruling through a petition for certiorari, arguing that the impeachment court committed grave abuse of discretion amounting to lack or excess of jurisdiction.

The possible challenge would put the constitutional text at the center of a dispute over whether “two-thirds of all the Members of the Senate” refers to the full 24-member Senate or only those able to participate when the final vote is taken.

Article XI, Section 3(6) of the 1987 Constitution provides that the Senate has the sole power to try and decide impeachment cases and that “no person shall be convicted without the concurrence of two-thirds of all the Members of the Senate.” 

The Senate majority, however, maintains that it did not reduce the constitutionally required two-thirds vote.

Senate President Sherwin Gatchalian said the issue decided by the impeachment court was not whether the two-thirds requirement should be lowered, but which senators should form the voting base when some members are unable to participate. 

Panelo rejected the argument that the Senate impeachment court’s unique constitutional character shields it from judicial scrutiny.

“Yung sui generis po kasi hindi po 'yan isang magic wand para hindi sundin ang Saligang Batas. Kahit sui generis ang Impeachment Court, kailangan sumunod ito sa due process, kailangan ito sumunod sa patakaran ng Saligang Batas,” he said.

The Supreme Court has previously recognized that the Senate, as a co-equal constitutional body exercising its impeachment functions, is generally beyond judicial control, but it also expressly said judicial review remains available in cases of grave abuse of discretion. 

In a 29 April ruling, the high court said the Senate’s exercise of its impeachment duties is beyond its power of review “except in cases of grave abuse of discretion.” The court was then reviewing a challenge involving the timing of the Senate’s convening as an impeachment court. 

Meanwhile, Panelo said Duterte’s possible appearance before the impeachment court remained unresolved. He said the defense had yet to determine whether the vice president should testify and raised the separate legal question of whether an impeached official could be compelled to testify against herself.

“Hindi pa namin napag-uusapan yan kasi unang-una may fundamental question kung napatunayan na ba ng prosecution yung kaso nila? Kasi ang burden of proof na sa kanila,” Panelo said.

“Meron pa kasing legal question, kung pwede ba talagang ipatawag ang isang akusado sa impeachment trial dahil merong karapatan ang isang accused to testify against herself,” he added.