A single vote could determine whether Vice President Sara Duterte is removed from office or acquitted, prompting former Senate President Franklin Drilon on Saturday to urge the Supreme Court to immediately settle a constitutional dispute over the number of votes required for conviction before the impeachment trial reaches its verdict.

Drilon warned that leaving the issue unresolved could plunge the country into a constitutional crisis if the Senate's final vote falls within the disputed threshold, opening the door to legal challenges regardless of the trial's outcome.

"Ultimately, ang Korte Suprema ang siyang magpapasya kung ano ba talaga ang kailangan na numero," Drilon said in a radio interview.

"Ngayon pa lang ay dapat desisyunan na ng Korte Suprema dahil kapag doon sa dulo, baka magkagulo," he added.

The controversy erupted this week after Senate President Francis Escudero, presiding officer of the impeachment court, ruled that 16 guilty votes would be required to convict Duterte, despite only 21 senator-judges currently being able to participate in the proceedings. 

Escudero based his ruling on Article XI of the 1987 Constitution, which states that "no person shall be convicted without the concurrence of two-thirds of all the Members of the Senate"—interpreting "all members" to mean the chamber's full complement of 24 senators. 

But the ruling immediately drew questions from constitutional lawyers, who argue that the two-thirds threshold should instead be computed based on the number of senators legally capable of sitting as judges.

The seemingly narrow difference has become potentially decisive because three senators are unable to participate in the trial.

Senators Rodante Marcoleta and Jinggoy Estrada are in detention after separate courts ordered their arrest on non-bailable plunder charges, while Senator Ronald dela Rosa has gone into hiding after the International Criminal Court issued a warrant for his arrest over his alleged role in former President Rodrigo Duterte's anti-drug campaign. 

If only 21 senators can vote, some legal experts contend that the constitutional threshold should effectively fall to 15 votes instead of 16. 

Under Escudero's interpretation, however, prosecutors would still need 16 votes—meaning they would have to secure more than two-thirds of the participating senators.

Drilon said the uncertainty should not be allowed to persist until the trial's conclusion.

He suggested that either the Senate impeachment court or Duterte herself immediately seek guidance from the Supreme Court on how the constitutional provision should be interpreted.

"Sabihing, 'hinihingi namin ang opinyon ng Korte Suprema alin ba ang tama dito, saan ba pagbabasihan ang two-thirds?'" he said.

The voting dispute adds another layer of uncertainty to an impeachment trial already viewed as a defining political battle ahead of the 2028 presidential election.

Duterte, a leading opposition figure and presidential contender, is facing charges that include alleged misuse of confidential funds, unexplained wealth, bribery, corruption and threats against President Ferdinand Marcos Jr.. Conviction would permanently bar her from public office. 

Last year, the Supreme Court nullified an earlier impeachment complaint against Duterte for violating the Constitution's one-year bar on successive impeachment proceedings. The current trial proceeded only after the House of Representatives transmitted a new complaint outside that prohibited period.

With months of testimony still expected, Drilon said resolving the voting issue now would prevent the impeachment court's eventual decision from being overshadowed by a constitutional battle over how many votes it actually took to decide the political future of the country's second-highest elected official.