The Philippine Supreme Court voted on Friday to remove its top judge, whom President Rodrigo Duterte has called an "enemy" for voting against several controversial government proposals, citing violations in the way she was appointed.
But one opposition party said the ouster of Maria Lourdes Sereno, the country's first woman chief justice, removed a shield against abuse of power in government and left behind a "puppet Supreme Court".
By a vote of 8-6, the court granted the government's petition to cancel Sereno's appointment on the grounds of alleged violations in the appointment process.
"Maria Lourdes Sereno is found disqualified from, and hereby adjudged guilty of unlawfully holding and exercising, the office of the chief justice," said court spokesman Theodore Te, who read out the decision.
The decision declared Sereno's position vacant with immediate effect and ordered the judicial and bar council to begin a new selection process, Te said.
The court gave Sereno a deadline of 10 days after receiving a copy of its decision to explain why she should not be sanctioned for a number of alleged violations, such as "casting aspersions and ill-motive to the members of the Supreme Court".
Sereno has denied any wrongdoing, and her spokesman said she would appeal the decision. "It is a sad day," Jojo Lacanilao said in a television interview.
Before the vote, dozens of Sereno's supporters held a vigil outside the court in the capital, Manila, demanding that the petition be thrown out and that she face trial in the Senate. Anti-Sereno protesters also gathered outside the building.
Opposition party Akbayan said the country was "a heartbeat away" from the death of its democracy.
"The ouster of our chief justice - this foundation of democracy, this shield against abuse of power in government - has crumbled," it said in a statement.
"After having a lapdog Congress and a seriously wounded Senate, we now have a puppet Supreme Court."
Duterte has made no secret of his dislike of Sereno.
She voted against several of his proposals, such as extending martial law on a restive island and allowing late dictator Ferdinand Marcos to be buried in a cemetery for national heroes.
In October last year, Duterte dared Sereno to open her bank account to public scrutiny, accusing her of corruption and of being used by his political opponents.
The decision came three days before Congress, controlled by Duterte's allies, returns from its Easter break to vote on an impeachment complaint against Sereno.