Anders Behring Breivik has been declared sane and sentenced to prison for bomb and gun attacks that killed 77 people last year.
Reading the ruling, Judge Wenche Elisabeth Arntzen handed down a sentence of “preventive detention” of at least 10 years and a maximum of 21 years.
However such sentences can be extended under Norwegian law as long as an inmate is considered dangerous.
Lawyers for the 33-year-old right-wing extremist said before the decision that Breivik would appeal any insanity ruling but accept a prison sentence.
Breivik, a 33-year-old Norwegian on a mission to expel Muslims from Europe, set off a car bomb that killed eight people outside government headquarters in Oslo, and then killed 69 others in a shooting rampage on Utoya island, where young members of the governing Labour Party had gathered for their annual summer camp.
Breivik will be taken back to Oslo’s Ila Prison, where he has been held in isolation for most of the time since his arrest.
Prisoners at Ila have access to schooling that offers courses from primary grade to university level courses, a library, a gym, work in the prison’s various shops and other leisure activities.
Because Breivik is held in isolation, he does not have access to those things. In compensation, Ila has given him three cells instead of one, each about 86 square feet.
One has gym equipment, another has a bed and the third a desk with a laptop computer. For at least an hour a day, he has access to a small courtyard covered by barbed wire.
Legal experts say it is unlikely Breivik will ever be released. It will not happen for as long as Norwegian authorities consider him dangerous to society.
During the trial he said that being sent to an insane asylum would be the worst thing that could happen to him and accused Norwegian authorities of trying to cast him as sick to deflate his political views.
His lawyers say Breivik is already at work writing sequels to the 1,500-page manifesto he released on the internet before the attacks.