By The South Asia Times

MANILA -  Philippine Vice President Sara Duterte is set to face the most consequential political and legal challenge of her career as the country's Senate convenes as an impeachment court on Monday to begin proceedings that could determine both her future in office and her prospects of contesting the 2028 presidential election.

The trial, expected to last several weeks or months, marks the first time in Philippine history that a sitting vice president has been tried in an impeachment court. If convicted by at least two-thirds of the Senate, Duterte would be removed from office and could also face a lifetime ban from holding any public office, effectively ending her widely anticipated bid for the presidency, according to local media outlet Inquirer. 

The Senate will begin the proceedings with opening statements from both the prosecution and defense, while senators acting as judges are expected to settle procedural matters before witness testimony and evidence are presented in later hearings.

The impeachment proceedings come after the dramatic collapse of the political alliance between Duterte and President Ferdinand Marcos Jr., whose UniTeam coalition won a landslide victory in the 2022 national elections.

Their relationship has since deteriorated into one of the country's most bitter political rivalries, transforming the impeachment trial into a broader struggle that could reshape Philippine politics ahead of the next presidential election.

Political analysts say the outcome will influence not only Duterte's political future but also public confidence in the country's democratic institutions.

Ederson Tapia, a political scientist at the University of Makati, described the case as a defining moment for constitutional accountability.

"This impeachment trial will likely define not only the political future of Vice President Sara Duterte, but also the credibility of our constitutional institutions," he said.

He added that the proceedings would test whether impeachment remains an effective constitutional mechanism for accountability or has become another arena for partisan political conflict.

- Charges against the vice president

The articles of impeachment accuse Duterte of multiple constitutional and criminal violations, including:

• Misusing 612.5 million Philippine pesos (about US$10.5 million) in confidential government funds.
• Allegedly threatening President Marcos, First Lady Liza Araneta-Marcos and former House Speaker Martin Romualdez.
• Bribing officials while serving as education secretary to circumvent government procurement rules.
• Amassing unexplained wealth through financial transactions allegedly involving billions of pesos over two decades.

The unexplained wealth allegations stem from reported discrepancies between Duterte's publicly declared statements of assets and information allegedly compiled by the Anti-Money Laundering Council.

Duterte has consistently denied all allegations and maintains she has committed no wrongdoing.

- Political battle ahead of 2028 election

Despite months of controversy, Duterte remains among the country's strongest potential candidates for the 2028 presidential election, making the impeachment proceedings far more than a legal exercise.

Political observers say the trial has effectively become the opening battle in the race to succeed President Marcos, who is constitutionally limited to a single six-year term.

Dennis Coronacion, chairman of the Political Science Department at the University of Santo Tomas, described the proceedings as "a battleground for the 2028 presidency."

Arjan Aguirre, assistant professor of political science at Ateneo de Manila University, said public perception of the Senate's impartiality would be critical.

"Given the Senate's current political composition, there will inevitably be concerns about whether partisan loyalties could influence the process," he said.

"The legitimacy of the trial will depend not only on how the Vice President defends herself but also on whether the Senate demonstrates that its verdict is grounded in evidence and constitutional duty rather than political alliances."

- Opening phase begins

The Senate has scheduled Monday's session primarily for opening arguments and procedural matters.

No witnesses are expected to testify during the first day.

Instead, prosecutors and defense lawyers will outline their respective cases while senators formally organize the proceedings.

The vice president may appear personally before the impeachment court or be represented by legal counsel.

House prosecutors say they are prepared to present documentary evidence supporting each impeachment article and expect the defense to challenge both witnesses and official records throughout the proceedings.

The Senate has allocated 62 hearing days for prosecutors and 30 days for Duterte's defense team.

- Historic constitutional process

The case is unprecedented in Philippine political history.

Sara Duterte is the first sitting vice president to face impeachment before the Senate and only the fifth senior constitutional official whose impeachment case has reached trial.

It is also only the third time the Philippine Senate has convened as an impeachment court.

The first high-profile impeachment involved former President Joseph Estrada in 2000, whose trial collapsed after prosecutors walked out over a dispute involving bank records. Estrada was later forced from office during mass protests known as the "EDSA People Power II" movement.

The second impeachment trial occurred in 2012, when Chief Justice Renato Corona was convicted and removed from office over allegations that he failed to fully disclose his assets.

Sara Duterte is the daughter of former President Rodrigo Duterte and served as mayor of Davao City before becoming vice president in 2022. She initially enjoyed strong public support after joining forces with Ferdinand Marcos Jr. in the UniTeam alliance, which secured a landslide electoral victory.

However, political tensions between the two camps steadily intensified after the election, culminating in public disagreements over government policies, cabinet appointments and budget issues. The alliance eventually fractured completely, setting the stage for one of the Philippines' most consequential political confrontations in recent decades.

The impeachment trial is expected to dominate Philippine politics for months and could significantly influence the country's political landscape ahead of the 2028 presidential election, while serving as a major test of the nation's constitutional accountability mechanisms.