Thousands of Sri Lankan lawyers and opposition supporters have clashed with government supporters over moves by parliament to dismiss Chief Justice Shirani Bandaranayake.
Government supporters armed with clubs tried to attack the protesters but were stopped by police.
The government accuses the judge of corruption - which she denies.
It is expected to win Friday's impeachment vote despite two court rulings that the process is illegal.
Ms Bandaranayake's supporters accuse the government of pursuing an unconstitutional vendetta against her.
Opposition and civil society activists say the impeachment is just the latest scheme in a government plan to bully the judiciary and lawyers.
Work in courts was halted on Thursday as hundreds of lawyers stopped work to take part in the protests, which ended when police blocked their route after they were twice confronted by government supporters.
A witness told the BBC they had threatened to crack her skull if she marched.
The government wants to remove Ms Bandaranayake because it says she has kept undisclosed bank accounts and has amassed undeclared sums in foreign currency or engaged in financial misconduct. She has strenuously denied the charges.
The BBC's Charles Haviland in Colombo says that impeachment will have unpredictable consequences because the government is pressing ahead with it in defiance of orders from both the Supreme Court and the Court of Appeal.
Our correspondent says that parliament, packed with government MPs, will vote to sack the chief justice on Friday. But given the court orders in her favour, it could be that she will refuse to go, triggering a constitutional crisis.
Last month she was declared guilty by a parliamentary committee minus opposition members who had walked out.