If confirmed, the Oslo district court will find itself in an unusual situation with two psychiatric examinations which each draw opposite conclusions but which both meet the proper quality requirements.
A first evaluation conducted last year by two court-appointed psychiatrists found Breivik, a 33-year-old rightwing extremist, to be psychotic, suffering from "paranoid schizophrenia".
That diagnosis would likely lead to Breivik being sentenced to a closed mental ward rather than prison.
But a second opinion, which the court ordered after the first one sparked a controversy, concluded that Breivik was sane enough to be held criminally responsible for his actions.
A panel of experts tasked with verifying the quality of the evaluations had approved the findings of the first exam, but last month asked the authors of the second opinion to provide supplementary information.
The panel said that in the second report, the two psychiatrists had not sufficiently taken into account the fact that Breivik may have adjusted his behaviour and remarks so as to be found sane, which he wants.
According to Norwegian media, the panel of experts have now approved the second opinion as valid after having received the additional information, though they have asked the two psychiatrists to answer certain questions when they testify in court at the end of June.
The question of Breivik's sanity is a focal point of his trial.
Breivik wants to be found sane so that his 1,500-page Islamophobic manifesto is not considered the ravings of a lunatic.
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On July 22nd, Breivik first set off a bomb near government offices in Oslo, killing eight people, before going to nearby Utoeya island where he killed 69 people, mostly teens, attending a Labour Party youth camp.
If he is found sane, he faces a 21-year jail term which could be extended indefinitely if he is still considered a threat to society. If he is found insane he could receive closed psychiatric care, possibly for life.
It will ultimately be up to the Oslo court judges to decide when they hand down their verdict in July.