The Senate impeachment court has significant powers as the sole tribunal for trying impeachment cases, which is provided for under the 1987 Constitution.

Legal luminaries said once the court convenes, even the Supreme Court cannot intervene in the proceedings.

Under Article XI, Section 3(6) of the 1987 Philippine Constitution, the Senate is vested with the “sole power to try and decide all cases of impeachment.”

This makes the Senate the exclusive tribunal for adjudicating impeachment proceedings, with no other body, including the Supreme Court, having primary jurisdiction over the trial.

The Senate President typically presides over the trial, except when the President of the Philippines is on trial, in which case the Chief Justice of the Supreme Court presides (Article XI, Section 3(6)), yet there is a school of thought that says the Chief Justice should be the presiding officer along with the Senate President as in the trial of former President Erap Estrada that had Senate President Aquilino Pimentel Jr. and Chief Justice Hilario Davide as officers.

The Senate has wide latitude in conducting an impeachment trial, including setting its own rules of procedure, determining the admissibility of evidence, and managing the trial process.

The guidelines are found in the Senate Rules of Procedure on Impeachment Trials, which is adopted for each case.

The Senate can summon witnesses, compel the production of documents, and administer oaths. It has the power to hold individuals in contempt for non-compliance with its orders during the trial.

In the same manner, it can hold the House prosecutors in contempt if they refuse to accept the impeachment complaints returned to them.

The impeachment court is also not strictly bound by the technical rules of evidence applied in regular courts, allowing for flexibility in evaluating testimony and evidence, as it is both a legal and political process.

Once the Senate renders a judgment, the House has no authority to challenge or override the decision. The House’s role ends once it transmits the articles of impeachment to the Senate. The Senate’s decision is binding, as it is the sole tribunal with adjudicatory powers.

The Supreme Court does not have direct authority over the Senate impeachment court’s decisions, but it can intervene in impeachment-related matters under its judicial review powers (Article VIII, Section 1) when there is a grave abuse of discretion amounting to a lack or excess of jurisdiction, according to a law expert.

The Supreme Court may review the constitutionality of actions taken by the House or Senate during the impeachment process, such as the validity of the impeachment complaint or its filing process in the House, and the Senate’s compliance with constitutional requirements, such as due process or quorum rules.

A case pending with the Tribunal questions whether the impeachment process may have breached the bar for one case filed a year, since the complaint against VP Duterte was based on a fourth complaint last year.

Impeachment proceedings are political processes tied to the specific Congress in which they are initiated; thus, an impeachment complaint filed in the 19th Congress does not automatically carry over to the 20th Congress.

There is no explicit constitutional provision addressing the carryover of impeachment cases across Congresses, but the structure of the Constitution suggests that the House’s initiation role is specific to a Congress session while the Senate’s trial role may extend beyond a single Congress.

The uniqueness of the impeachment court, which the late Senator Miriam Santiago called sui generis, requires the House prosecutors and the senator-judges to fulfill their roles. Prosecutors must follow the court’s decision.

The alternative is that the process fails, which offers room for yellow mayhem.