The Philippines' first impeachment trial of a Supreme Court justice began Monday.

Members of the 23-person Senate will sit as judges to determine whether Supreme Court Chief Justice Renato Corona should be removed from his post.

The Philippine constitution requires a two-thirds endorsement of the senators, or 16, for Corona to become the first Philippine chief justice to be sacked.

Senate President Juan Ponce Enrile promised his chamber would hold an impartial and fair trial, but warned its impact would affect the nation.

“The ostensible respondent in the trial before us is the Chief Justice of the Supreme Court, we cannot escape the reality that in a larger sense, the conduct of this trial and its outcome will necessarily have a serious impact on the entire nation.”

Corona was impeached by the House of Representatives in December on corruption allegations as well as accusations that he tried to block prosecution of former President Gloria Macapagal Arroyo.

He has denied any wrongdoing.

Ms. Arroyo was detained in November on charges of rigging the 2007 senatorial elections.

The trial is the latest struggle in a political drama pitting President Benigno Aquino against Ms. Arroyo, his predecessor, whom he blames for a decade of corruption scandals that eroded public trust in government.

Mr. Aquino won a landslide election victory in 2010 largely on a platform to end corruption.

Scores of activists protested outside the Senate in support of the impeachment trial.

“Ultimately, we want to see the process pave way for former President Gloria Macapagal Arroyo's accountability for her crimes. But they should not use the trial for any other purposes but to make them accountable,” said New Patriotic Alliance spokesperson Renato Reyes.