A widely used problem-solving principle called the law of parsimony states that when presented with competing explanations for an event, the one that makes the fewest assumptions is usually correct.

Retired Supreme Court Associate Justice Adolfo Azcuna, one of the framers of the 1987 Constitution, gave the simplest interpretation on Wednesday of the provision setting the conviction threshold for Vice President Duterte: all means all.

This means that with 24 members in total, the two-thirds threshold to secure a conviction is 16, regardless of how many senator-judges attend the trial, he said.

Azcuna’s position, however, differed from those of retired SC chief justices Hilario Davide Jr., Reynato Puno and Artemio Panganiban.

The Senate impeachment court tapped them as amici curiae (friends of the court) to advise the senator-judges on how to lawfully interpret Article XI, Section 3(6) of the 1987 Constitution to prevent a possible deadlock on the day of judgment amid the absence of four of their colleagues, who may be unable to vote.

“I respectfully submit, your honors, that the reference in this provision is to all members of the Senate. As long as they are members of the Senate, they constitute the denominator and compute the threshold of two-thirds because all means all,” Azcuna said.

He warned that lowering the threshold to a simple majority would allow a dominant faction in the Senate to have the upper hand in determining the outcome, reducing the trial to a mere “formality rather than a genuine deliberative check.”

Azcuna argued that the framers intentionally set a higher threshold, requiring a supermajority, to insulate impeachment proceedings against “factional and partisan abuse.”

“Impeachment is a political judicial hybrid exercise. It is not an ordinary voting procedure. [It] removes a sitting publicly accountable official often directly elected before the end of a fixed term,” he said.

Higher bar to convict

A convicted impeached official faces removal from office and perpetual disqualification from holding future office.

Azcuna noted that these serious penalties were precisely why the framers of the Constitution deliberately set a higher bar to convict an impeached official because a conviction in this proceeding is “final and largely irreversible.”

“A decision this hard to undo warrants a higher threshold of agreement than routine business,” he said.

“The framers […] feared that impeachment could become a tool for a transient legislative majority to remove a political rival or an official from this favored party, effectively overturning an election resolved through legislative fire rather than through the ballot box,” he pointed out.

Senators Jinggoy Estrada, Rodante Marcoleta — both detained on plunder charges — and Ronald “Bato” dela Rosa, who remains in hiding to evade an International Criminal Court warrant, have not attended Duterte’s trial since it began on 6 July.

Senator Loren Legarda has missed the proceedings since 3 August when she went on a medical leave abroad amid a preliminary investigation into plunder and graft complaints by the Ombudsman.

Critics have argued that their absence effectively altered the Senate’s composition and thereby necessitated lowering the conviction threshold base from 24 to either 20 or 21.

Azcuna, however, cautioned that reducing the threshold base to a simple majority or two-thirds of the quorum present would make conviction achievable by the coalition that dominates the Senate.

“Requiring two-thirds forces conviction to rest on a coalition that cuts across ordinary partisan lines, which is precisely the point,” he argued.

Does not apply

More importantly, Avelino v. Cuenco — the ruling previously used by the Senate to establish a quorum of only 12 — does not apply to Duterte’s impeachment case, Azcuna said.

This is mainly because the Supreme Court’s jurisprudence was based on the 1935 Constitution, which has a “different” wording from the 1987 Constitution, he said.

“The quorum requirement under the 1935 Constitution said a majority of the Senate. It didn’t say all the members,” he said.

As for allowing senator-judges who miss a substantial part of the trial to vote, Azcuna said the Senate should allow them given that the proceedings are recorded. A transcript is available for their review, he added.

Several senators had raised concerns that, because some of their colleagues cannot monitor the proceedings, they cannot “vote intelligently” and may end up voting solely along political lines.

For these reasons, Azcuna maintained that an impeached official shall only be convicted with the concurrence of two-thirds of all the 24-member Senate.

The Senate impeachment court is set to put to rest the debate on whether to maintain or lower the threshold on 23 September, after the defense and prosecution panels present their respective positions in oral arguments, which will be held the same day.

Tijam backs 16

Former Associate Justice Noel Tijam said that while he respected the opinions of Davide, Panganiban, and Puno, he agreed with Azcuna.

This position is more consistent with the Constitution’s wording, how the Constitutional Commission deliberated, and how the Filipino people who ratified the Constitution understood it, the former magistrate said.

When the Filipino people ratified the 1987 Constitution, was it explained to them that the mandated 2/3 vote result to convict an impeachable officer “can be diluted, diminished, or reduced depending on contingent circumstances?” Tijam asked.

“Will the senators prevented from voting be legally allowed to be disenfranchised from exercising their rights and privileges without judicial sanction or constitutional basis?” the former SC member asked.

“The opinion of three learned former Chief Justices would not be enough to be accepted with certitude or finality, with due respect,” he added.

According to Tijam, only a final ruling by 15 Supreme Court justices deliberating en banc will suffice under the Constitution.

“The Filipino people should have decided the question of fitness or suitability of the Vice President in a national election,” he said. Impeachment is a political act.