The Senate risks committing “grave abuse of discretion” if it resists convening as an impeachment court to try Vice President Sara Duterte, in favor of the majority decision by its members, a legal expert warned Thursday. 

Lawyer Tranquil Salvador III, dean of the School of Law and Jurisprudence of the Manila Adventist College and professorial lecturer of the Philippine Judicial Academy, raised the issue on the heels of reports that the Senate may not convene as an impeachment court if the majority of the senators would vote against it, according to Senator Ping Lacson.

"Can that be a question of grave abuse of discretion? In my opinion, yes,” he said in a radio interview, adding that senators are mandated to do so under the Constitution.

Salvador warned that this would be an “issue of first impression,” and may trigger constitutional concerns.

Salvador had previously participated in impeachment trial proceedings, serving as a spokesperson and part of the defense team of the late Supreme Court chief justice Renato Corona, who was impeached in 2012.

An associate dean and a constitutional law professor at the University of the Philippines Diliman, lawyer Paolo Tamese, echoed the same concern. He argued that the Senate is constitutionally bound to act on any impeachment cases, which could be initiated by convening as a court.

He, however, said this could still be overridden by political dynamics, as seen last year, when the House of Representatives first impeached Duterte, but was not tried in the Senate due to efforts to block it.

“The Senate rules by a majority vote and therefore things may deviate from constitutional design….But in theory, as a matter of duty, they have the duty to take on this case and rule upon it if it does, in fact, go to the Senate," Tamese told ANC.

He believes that the Senate’s potential defiance may prompt new Supreme Court petitions and could derail the looming trial of Duterte, as was the case last year. 

The Senate was embroiled in a similar controversy earlier last year over efforts by pro-Duterte senators to block the trial by insisting that the proceedings cannot be carried over from the 19th Congress to the 20th Congress. 

Recall that Duterte was first impeached by the House of Representatives on 5 February last year, though the trial in the Senate did not commence forthwith since Congress went on a three-month break for the election campaign.

Although the Senate subsequently convened as an impeachment court in June, no trial proper was held because it returned the articles of impeachment to the House, further delaying the trial. 

Eventually, the Supreme Court ruled in July that the impeachment case against Duterte was unconstitutional and void for violating the one-year bar rule. 

Senate President Tito Sotto earlier vowed that the chamber would “act with dispatch” by convening as an impeachment court a day after it receives the articles of impeachment from the House.

Sotto’s approach stood in stark contrast to that of his predecessor, former Senate president Chiz Escudero, who drew widespread backlash last year for insisting that “forthwith” does not strictly mean “instant,” despite the Charter framers defining it as “without delay.”

However, following the recent SC ruling, which defines “forthwith” in the context of impeachment as “a reasonable period of time," and not instantly, Sotto said that although they would convene immediately, the trial proper would commence in due course.