Breivik, who killed 77 people in 2011, is being held apart from other inmates at a high-security facility.
He is suing the Norwegian state, accusing it of “inhuman” and “degrading” treatment in violation of the European Convention on Human Rights.
“If we have to, we will bring it … to the European Court of Human Rights,” Breivik's lawyer Oystein Storrvik told AFP in an interview.
“Isolation has been damaging to his psychological health,” he said.
“One of his main things to do (in prison) was to study and he has stopped that now, and I feel that is a sign that isolation has been negative to his psychological health,” he added.
In a document submitted to the Oslo district court and published on Wednesday, the office of the attorney general, which is defending the state in the case, said Breivik's prison conditions were “well within the limits of what is permitted” under the Convention.
Breivik has access to three cells — one for living, one for studying, and a third for physical exercise — as well as a television, a computer without internet access and a PlayStation game console. He is also able to prepare his own food and do his own laundry, the document said.
While he is allowed no contact with other inmates, also for security reasons, he interacts with guards and professional staff.
Breivik also accuses the state of violating another aspect of the Convention, regarding his right to privacy, for censoring his mail.
Authorities have said those restrictions are necessary to prevent him from building up an “extremist network”.
On July 22, 2011, Breivik killed eight people in a bomb attack outside a government building in Oslo and later murdered another 69 people, most of them teenagers, when he opened fire at a Labour Youth camp on the island of Utøya.
He was given a 21-year prison sentence in August 2012, which can be extended if he is still considered a danger to society.
The case will for security reasons will be heard in the gymnasium of the Skien prison, about 100 kilometres (62 miles) southwest of Oslo where the 37-year-old killer is incarcerated, from March 15 to 18.