EXPLAINER: What are amici curiae?

Impeachment presiding officer Francis "Chiz" Escudero said Tuesday the Senate impeachment tribunal would invite amici curiae, or "friends of the court," regarding the voting threshold required to convict an impeached official.

But what does an amicus curiae do?

Black's Law Dictionary defines amicus curiae—the singular Latin noun for amici curiae—as "a bystander (usually a counsellor) who interposes and volunteers information upon some matter of law in regard to which the judge is doubtful or mistaken… or upon a matter of which the court may take judicial cognizance."

In the Philippines, the term may also be found in Section 10 of the Internal Rules of the Supreme Court (SC).

Though the section does not define the phrase, it states that, "if necessary, the Court may invite amicus curiae."

Section 23, Canon III of the Code of Professional Responsibility and Accountability (CPRA) also states that a "lawyer shall not decline, without just cause, a request by any court, tribunal, or other government agency to act as amicus curiae in any proceeding relating to the lawyer's expertise or field of specialization."

Over the years, the SC has invited amici curiae during its proceedings, including its recent oral arguments on unprogrammed appropriations in the 2024, 2025, and 2026 national budgets, and the petitions that sought to block the transfer of the Philippine Health Insurance Corporation's (PhilHealth) excess funds back to the national treasury, among others.

'Specific expertise'

University of the Philippines (UP) Law Assistant Professor Michael Tiu Jr. said amici curiae are called in to guide the court on questions of law or fact "where the court might not have a specific expertise."

"They are important because they provide guidance in answering a difficult question. Their expertise built through years of careful study support the quality of their analyses that courts need to aid them in deciding technical or difficult legal questions," Tiu said.

According to University of Santo Tomas (UST) Law Dean Atty. Nilo Divina, amici curiae are important because they "assist the court in resolving difficult, novel, or highly significant legal issues."

"While the parties naturally advocate for their respective positions, an amicus curiae provides an independent perspective that may help clarify the law, present broader policy considerations, or offer specialized expertise relevant to the case," Divina told GMA News Online.

Both Tiu and Divina, however, clarified that the court is not bound by the views of an amicus curiae.

Tiu said that after careful study of the amici curiae's inputs, the court can be "persuaded and adopt" their analyses, or it may "disagree and refute" the same.

For his part, Divina added, "It may consider and draw guidance from the amicus' submissions in understanding the legal, constitutional, or public-interest implications of the issues before it."

"Ultimately, the value of an amicus curiae lies in helping the court arrive at a more informed and well-reasoned decision," he added.

'Pabor man o kontra'

During the 23rd day of Vice President Sara Duterte's impeachment trial, Escudero similarly said the amici curiae may help the court through their knowledge.

"Sana sa pamamagitan ng kanilang kaalaman, at lawak ng kaalaman kaugnay sa batas, sa Saligang Batas, at gayon din karanasan nila sa mga legal na bagay ay mabigyan tayo ng kanilang kaisipan kaugnay sa issue na ito, pabor man o kontra sa pagkabilang panig," Escudero said.

(We hope that through their knowledge and breadth of knowledge regarding the law and the Constitution, and likewise their experience in legal matters, they can give us their thoughts regarding this issue, whether in favor of or against either side.)

Senator-judge Francis "Kiko" Pangilinan moved to authorize Escudero to select the amici curiae, provided that there are consultations with the parties.

For his part, Escudero said he has discussed the matter with the parties and had come up with names agreed upon by both the prosecution and the defense panels.

"We already talked about some retired justices of the SC but I'm not yet at liberty to state their names because we have not yet gotten in touch with them," he said earlier.

Escudero said the appearance of the amici curiae will be scheduled on September 16.

Meanwhile, Escudero said the impeachment will also schedule an oral arguments on September 23 for the prosecution and Duterte's defense team.

The discussion on inviting amici curiae was brought up after senator-judge Erwin Tulfo sought a clarification on Escudero's ruling that the base vote to convict an impeached official is all 24 senators.

In the past months, several personalities have expressed their opinion regarding the voting threshold, considering the arrest or absence of some senators as Duterte's impeachment trial progressed.

The 1987 Constitution states that "no person shall be convicted without the concurrence of two-thirds of all the Members of the Senate." — VDV, GMA News