MANILA - Opposition Senators Leila de Lima and Antonio Trillanes IV on Friday warned against the hasty resolution of the petition seeking to nullify Chief Justice Maria Lourdes Sereno's appointment.

The Supreme Court is expected to resolve on May 11 the quo warranto plea Solicitor General Jose Calida filed against Sereno, while an impeachment case remains pending against the chief magistrate at the House of Representatives.

• SC magistrates to vote on Sereno ouster on May 11 - source

The date comes before Congress resumes session on May 15.

• House to wait for SC decision on Sereno before impeachment

In a statement, De Lima and Trillanes called the Supreme Court's act to "take cognizance [of] and... expedite action" on the quo warranto plea against Sereno an "act of betrayal."

"It is a betrayal of the Filipino people who ordained and promulgated the Constitution. It is a betrayal of the Supreme Court’s duty to preserve and protect the powers exclusively vested in other branches of government," they said.

"It is a betrayal of the integrity of the Supreme Court itself. We refuse to watch silently while the Office of the Solicitor General bids the Supreme Court to sound the death knell of our democracy."

The two senators also warned the high court against overstepping its jurisdiction to remove impeachable officers.

"Kapag nilabag ng Judiciary ang eksklusibong kapangyarihan ng Kongreso na magtanggal sa pwesto ng mga impeachable officers, lalampas na po kayo sa boundary ng kapangyarihan ninyo, at nag-tre-trespass na po kayo sa teritoryo ng Lehislatura," they said.

(If the judiciary breaches the exclusive power of Congress to remove impeachable officers from their posts, you will exceed the boundary of your power and trespass into the territory of the legislature.)

De Lima and Trillanes cited one of former president Jose P. Laurel's decisions, in which he said "the separation of powers is a fundamental principle in our system of government."

"It is a landmark decision, and passages from it are routinely memorized by law students. Because if one is to understand one fundamental thing about the Constitutional structure of our government, that is it in a nut shell," they said.

"It is sacred, and to forget it is to forget the faces of our forefathers; and to betray it is to betray one of the very basic components that holds up this social contract between the State and its people."

The two senators earlier sought inclusion in the Supreme Court's proceedings on the quo warranto petition.

• De Lima, Trillanes seek dismissal of quo warranto case vs Sereno

Sereno, who is also facing an impeachment case, had earlier asked the court to throw out the Solicitor General's plea, arguing that she could only be removed through impeachment proceedings.

• Sereno urges SC to junk quo warranto petition seeking her ouster