Norway's most notorious inmate has been detained in a high-security prison unit since he massacred 77 people in a bomb-and-gun rampage in 2011.
The 37-year-old far-right extremist claimed at the March hearing into his lawsuit that his solitary confinement violated the European Convention on Human Rights.
But the state's lawyers argued that his isolation was necessary because Breivik is “extremely dangerous”, and said his conditions — which include games consoles, workout machines and three cells at his disposal for his various activities — fall “well within the limits of what is permitted” under the European convention.
Breivik is serving a maximum 21-year sentence — which can be extended if he is still considered dangerous — for killing eight people in a bombing outside a government building in Oslo and then shooting dead another 69, mostly teenagers, at a Labour Youth camp on the island of Utøya on July 22, 2011.
Disguised as a police officer, he spent more than an hour hunting down the almost 600 youths trapped on the small island.
He put a bullet in the head of most of his victims, some of them up-and-coming leaders of Labour, Norway's dominant political party, which Breivik blamed for the rise of multiculturalism.
Breivik used the four-day hearings — held in the gymnasium of Skien prison, about 130 kilometres (80 miles) southwest of Oslo, where he is held — to promote his extremist views.
After making a Nazi salute on the opening day of proceedings, he claimed he was now a Nazi who had renounced violence and even compared himself to Nelson Mandela.
Take case to Strasbourg?
Since his arrest on the day of the attacks, Breivik has been held apart from other prisoners and his contacts with the outside world, including visits and correspondence, have been strictly controlled.
He accused the state of breaching two clauses of the European convention prohibiting “inhuman or degrading treatment or punishment”, and guaranteeing respect for “correspondence”.
His lawyer, Øystein Storrvik, told the hearing the case was important as Breivik would probably spend the rest of his life behind bars.
Breivik said his solitary confinement had had negative effects on his health.
But doctors, psychiatrists and prison staff who examined him in prison testified they had seen no major change in his physical or mental state due to jail conditions.
Norway prides itself on a humane prison system aimed more at rehabilitation than punishment, and Breivik's conditions are considered comfortable by most.
The judges heard how Breivik has three cells at the Skien Prison — one for living, one for studying and one for physical exercise. He also has a TV with a DVD player, a games console, a typewriter, and books and newspapers.
The prisoner is “extremely dangerous” and must not be allowed to communicate with supporters who may carry out new attacks, authorities said, as they defended their use over the years of handcuffs, strip searches and strictly-controlled correspondence and visits.
“I think it's a strict regimen but based on the explanations given for it, I can't see anything to suggest that the convention has been violated,” law professor Kjetil Larsen told Norwegian news agency NTB.
“But one could argue that we are close to the limit for the extent of the isolation,” he added.
The verdict is to be delivered by email around 3pm (1300 GMT). There will be no hearing in session.
The ruling may however not be the end of the matter.
“If we have to, we will bring it … to the European Court of Human Rights,” Storrvik, Breivik's lawyer, told AFP in an interview in early March.