Former Supreme Court Associate Justice Antonio Carpio said the number of senators required to convict Vice President Sara Duterte in an impeachment trial could fall below 16, depending on how many lawmakers are able to participate in the proceedings.

Carpio said the voting threshold is not fixed and will depend on the total number of active senators when the Senate convenes as an impeachment court. The trial is scheduled to begin on 6 July.

The Constitution requires a two-thirds vote of all members of the Senate to secure a conviction. However, Carpio explained that the actual number needed may change if some senators are unable to vote.

He cited Sen. Jinggoy Estrada, who remains under detention and suspension by the Sandiganbayan. While Estrada retains his status as a senator, Carpio said his ability to participate in the impeachment vote could be affected.

Carpio also noted that Sen. Ronald dela Rosa, who is reportedly in hiding following the issuance of an arrest warrant by the International Criminal Court over the previous administration's anti-drug campaign, cannot yet be excluded from the voting count because he has not been arrested.

According to Carpio, the threshold could further decrease if other senators become unable to vote due to detention or other legal circumstances.

The former magistrate also warned that the impeachment process could be prolonged if the Senate impeachment court grants a motion to dismiss filed by Duterte's camp.

Carpio said prosecutors would likely elevate the matter to the Supreme Court, potentially extending the proceedings before the trial reaches its conclusion.