Egyptian police have broken up a pro-reform protest at the Judges' Syndicate in Cairo, beating one senior judge and detaining 15 protesters.
Judges have become figureheads for the reform movement
Fifty judges have been holding a sit-in at their headquarters to protest against the prosecution of two of their colleagues by the government.
Police moved against demonstrators overnight and struck a judge who came out to defend them, witnesses said.
Judge Mahmoud Hamza was taken to hospital but was not seriously hurt.
In an interview with the BBC, he said the government wanted to "terrorise" judges to back down from demanding their rights.
"In front of the gate, to my shock, someone snatched my phone out of my hand. Another came and held me from behind, and they dragged me across the road," Judge Hamza told the BBC Arabic service.
"I told them I was a judge, a head of a court, whack, they hit me," he said. "To my surprise they took my trousers off!"
President Hosni Mubarak has denied any attempt by his regime to interfere with Egypt's judicial system.
"I will not intervene between judges out of respect for the judiciary's independence and esteem for its judges," he said in an interview with al-Gomhuriya newspaper.
The judges' protest is set to continue until 27 April, when judges Hesham Bastawisi and Mahmoud Mekki will appear before a disciplinary hearing.
The judges - both members of the Court of Cassation, Egypt's highest appeals court - are being prosecuted after pressing for an inquiry into alleged electoral fraud in 2005.
Late last year, President Mubarak's ruling National Democratic Party won more than 70% of seats in parliamentary elections in a vote marred by violence and accusations of fraud.
The judiciary in Egypt is required to supervise elections, but many judges have been angered by what they regard as attempts by the government to exploit them to legitimise fraud.
Through their professional association, judges have issued reports detailing violations in last year's elections.
The association also continues to press loudly for a new law guaranteeing the independence of the judiciary.