One of the three lay judges trying Breivik was dismissed yesterday because he posted a comment on Facebook calling for him to be executed.
"The death penalty is the only just sentence in this case," read the message posted by Thomas Indreboe on July 23 last year, the day after Breivik killed 77 people.
Judge Wenche Elizabeth Arntzen ruled that he should be replaced by lay judge Elisabeth Wisloff, one of two backups.
Breivik is being tried by two professional judges and three lay judges for the crime of mass-killing with the aim of terrorising a population. It is they who will rule on whether he faces a maximum prison sentence of 21 years, or compulsory psychiatric treatment.
All cases heard before the Norwegian courts are presided over by a professional judge.
But they are assisted by non-professionals.
The system -- which is also used in Sweden, Germany and Japan -- ensures that citizens who do not have a law qualification play a key role in the country's legal system.
Lawyers on all sides requested Mr Indreboe be taken off the trial, saying the comments violated his impartiality.
Anyone selected as a lay judge is obliged to accept the office.
However, certain occupational groups are exempt, including judges, police officers and prosecutors, employees of the Ministry of Justice and the National Courts Administration. (© Daily Telegraph, London)