A fourth challenge to the Senate's trial rules is in front of the Supreme Court, and it was filed by two of the Vice President's own allies in the chamber that will vote.
Sens. Robinhood "Robin" Padilla and Christopher "Bong" Go, together with the Partido Demokratiko Pilipino-Lakas ng Bayan (PDP-Laban), asked the Supreme Court on Sept. 29 to stop the Senate from using what they call an "unconstitutional denominator" in the impeachment trial of Vice President Sara Duterte, according to INQUIRER.net's Kathleen de Villa. The petition for certiorari and prohibition runs 106 pages, the Inquirer reported in a story dated Oct. 7. De Villa's report describes PDP-Laban as the party of the Vice President's father.
The argument
The petitioners contend that the Senate ruling lowering the number of votes needed to convict or acquit is unconstitutional. They say the trial itself can continue, and describe their request as "a narrow remedy": stop the use of the lowered denominator, including any move to exclude sitting senators from the count. Per the Inquirer, they note that 24 senators remain because no seat has been vacated by death, resignation, forfeiture or cancellation, and that under the 1987 Constitution's two-thirds rule this means 16 votes. They also argue that the Constitution's reference to "all" senators cannot be read to mean only some of them.
Pulpulitiko has previously reported that the Senate's rule leaves the conviction threshold at 14 votes. The gap between 14 and 16 is the entire point of the fight: two votes in a 24-member chamber.
The Court has already ducked it
The Inquirer reports the Supreme Court dismissed three earlier petitions challenging the same ruling the day after this one was filed. Pulpulitiko reported that the En Banc did so on standing and prematurity grounds, without saying whether the lower threshold is constitutional. The Inquirer article does not summarize the Court's reasoning, and the new petition's fate is not stated. The article reports no timeline for the Court to act.
That makes the new filing's timing awkward for its authors. The justices had just declined to reach the merits on three other petitions, and the senators here are not outsiders. They sit in the body whose rules they are challenging, and are, in the trial's terms, among the people who will count the votes. Whether that cures the standing problem, or only raises it, is a question the sources reviewed do not answer.
Responses
The Inquirer's report includes no response from the Senate, the Supreme Court or the Vice President's camp, and this reporting did not find one elsewhere. The named respondents in the petition are likewise not identified in the article.
Context
The impeachment trial is deep into its evidence phase, with prosecutors presenting bank records and AMLC testimony in recent sessions, as Pulpulitiko has reported. A final vote is still some way off, but the threshold question will decide what counts as a conviction when it arrives. Nobody on either side disputes that the denominator matters.
What is not known
- Whether the Court will act on the petition before the Senate votes.
- Whether the Court sees Padilla and Go's position as senators as giving them standing the earlier petitioners lacked.
- Whether the Senate will formally answer the petition.
Sources
- Kathleen de Villa, "Senate vote threshold ruling questioned anew in SC by Duterte allies," INQUIRER.net, Oct. 7, 2026 — https://newsinfo.inquirer.net/2319139/senate-vote-threshold-ruling-questioned-anew-in-sc-by-duterte-allies
- Pulpulitiko, "Supreme Court Junks Challenges to Senate's Lower Conviction Threshold — Without Saying Whether It's Constitutional," Oct. 4, 2026
- Pulpulitiko, "Senate Sees 30 Bank Accounts Holding About ₱190 Million Against ₱13.3 Million in Sara Duterte's SALN," Oct. 7, 2026