Police say about 1,800 protesters gathered by midmorning to help Sereno exterior the court docket in Manila the place anti-riot policemen blocked an entry street with vans and iron railings to keep up order.
Philippines Supreme Court justices, in a historic decision Friday, removed their own chief justice, Maria Lourdes Sereno, a known critic of President Rodrigo Duterte.
He emphasized that in impeachment, the SC can not be supreme "because the Senate is the one and only impeachment court" and the only way to remove the Chief Justice is for the House to impeach her and for the Senate to convict.
"Respondent Maria Lourdes P.A. Sereno is ordered to show cause within ten days from receipt hereof why she should not be sanctioned for violating the Code of Professional Responsibility and the Code of Judicial Conduct for transgressing the sub judice rule and for casting aspersions and ill motives to the members of the Supreme Court".
"You can not issue a quo warranto to remove an impeachable official and the system that judges you should not be the one who accuses you".
"This is more than a wake-up call".
Her expulsion from the high court marks the first time that a chief justice was removed through a "quo warranto" plea, a legal recourse Sereno's camp had argued as incorrect.
Critics warned the court action would set a unsafe precedent and give the Duterte administration a legal weapon to muzzle dissent.
Opposition leader Senator Francis Pangilinan says Congress should insist on its exclusive constitutional role to remove key officials like Sereno through impeachment.
She said she wants to talk to common people, including the youth, about injustice and the urgency of fighting for what is right.
"To correct this wrong, we urge the Senate, as the body mandated in the Constitution in impeachment proceedings, to question the Supreme Court ruling". Let the trial in the Senate, sitting as an impeachment court, begin. In 2016, after Duterte accused some public figures and judges of being involved in the drug trade, Sereno angered the president by instructing judges not to turn themselves in to authorities before being presented with a warrant. "And you have to be out of the Supreme Court", Duterte said in a speech last month, in which he said he requested lawmakers to "go into the impeachment right away"'. Renato Corona was impeached in 2011 for betraying the public trust and committing culpable violation of the Constitution. "So she's ousted as chief justice because that's her only position".
Sereno told the crowd: "Let's continue to defend the constitution and fight wrongdoing".
Sereno had called on six of her colleagues, who testified against her in House impeachment hearings, to abstain from Friday's vote citing their bias.
Worldwide rights groups and local critics have accused Duterte of drifting toward authoritarianism after declaring martial law in the south amid a major attack by pro-Daesh militants a year ago.
The Philippines lived under martial law a generation ago, when dictator Ferdinand Marcos used military rule to suppress his critics.