PASAY CITY — Surprise witnesses in the impeachment trial of Vice President Sara Duterte will not be barred from testifying even if they are not initially listed in the parties’ pre-trial briefs, provided that at least three days’ notice is given before their appearance, Senate Secretary Renato Bantug confirmed Monday.

Bantug, who serves as clerk of the Senate impeachment court, said the practice is consistent with existing court procedures.

“Both parties have the right to make reservations as to witnesses who may not be available yet during pre-trial,” he told reporters on the sidelines of the second day of the pre-trial conference.

He explained that because the procedure is “allowed in the rules of court,” the Senate impeachment court would likewise recognize it.

Under the arrangement, both the prosecution and the defense must notify each other at least three days before presenting any witness who was not previously identified during pre-trial proceedings.

The parties are required to disclose their prospective witnesses during the pre-trial conference, a closed-door proceeding designed to streamline the trial and narrow the issues for litigation.

However, Bantug said the rules do not prohibit the addition of witnesses at a later stage, as long as sufficient notice is provided to avoid trial by ambush and ensure fairness to both sides.

The possibility of surprise witnesses is not new in Philippine impeachment proceedings.

During the impeachment trial of former President Joseph Estrada in 2000, the House prosecution presented then-Equitable PCI Bank Senior Vice President Clarissa Ocampo as a surprise witness.

Ocampo testified that she personally witnessed Estrada sign bank documents under the alias “Jose Velarde” in Malacañang, linking the former president to alleged ill-gotten wealth and a multi-billion-peso bank account.

Her testimony became a pivotal moment in the proceedings and helped fuel the events that culminated in the EDSA II uprising, which led to Estrada’s ouster on 20 January 2001.

In Duterte’s impeachment case, House prosecutors have previously ruled out presenting surprise witnesses. They earlier disclosed that at least 57 witnesses could potentially testify once the trial begins on 6 July.

The prosecution and defense continued their pre-trial conference Monday and are aiming to complete the marking of evidence and other preparatory matters before drafting the pre-trial order for submission to the impeachment court.