Streets around a Cairo courthouse were cordoned off as two senior judges were facing a disciplinary hearing.
Thousands of riot police were drafted in to prevent demonstrations in support of the pro-reform judges.
But protesters took to the streets and demonstrations turned violent with police and protesters clashing.
Opposition groups say dozens of their members have been taken into custody.
The judges, who did not appear in court, spoke out against fraud in elections last year and are now facing dismissal.