How to defend a mass-murderer whose guilt is not in question? Anders Behring Breivik's defence will take the unusual approach of trying to prove he is criminally responsible and should be sent to prison.
The 33-year-old right-wing extremist who killed 77 people in twin attacks last July has said he does not want his lawyers to try to get him a light sentence, but rather wants them to focus on arguing that he is of sound mind.
Their strategy received a boost this week when a second psychiatric examination concluded Tuesday that Breivik was not psychotic at the time of the massacre, contrary to the findings in an initial probe late last year.
"Breivik is very clear on this point: he believes his message would be delegitimised, as he says, if he is declared criminally insane," one of his lawyers, Vibeke Hein Baera, told AFP.
The confessed killer had told the first two psychiatric experts who examined him that the carnage had been "just a formality" aimed at drawing attention to his "manifesto" –a more than 1,500-page Islamophobic rant published shortly before the attacks.
By concluding that he suffered from "paranoid schizophrenia" the two experts not only sparked a heated debate in Norway but also dealt a blow to the killer's ambition to spread his ideas as a serious ideology and not the rantings of a crazy person.
In a letter to Norwegian media last week, Breivik acknowledged that the first expert conclusion was "the ultimate humiliation," and insisted that being sent to a psychiatric hospital instead of prison would be "a fate worse than death."
His desire to be found sane has put the defence in the unusual position of pushing a line that leads directly to prison, while the prosecution has said it may ask for Breivik to be declared criminally insane and to be sent to a closed mental ward.
"We have in part changed our strategy after he himself did an about-face on what he wanted," chief defence lawyer Geir Lippestad told AFP, pointing out that he and his colleagues had given up searching for extenuating circumstances.
If the defence had argued criminal insanity, he said, it would have pointed to the fact that Norway might have given Breivik too much room to manoeuvre.
"How was this possible? Why did he not receive help (for his hypothetical illness)? Why was he not detected?" were among the questions Lippestad said he could have asked if the line of defence had been different.
"But since he today wants to be declared criminally responsible, this line of argumentation is void. It is no longer valid, since it would possibly contribute to him being found criminally insane," he explained.
In addition to medical experts, the defence plans to call a number of both right-wing and Islamic extremists as witnesses to show that Breivik's world view, which was dismissed by the first psychiatric experts as "delirious", is shared by others.
"When you read the report from the first psychiatric experts, they explain their diagnosis by the fact that Breivik lives in a reality that no one else recognises, an unreal world," Lippestad pointed out.
"For us, it is therefore important to see if others, even if they make up a tiny minority, share this reality and also think that the Christian and Muslim worlds are at war," he added.
Faced with two psychiatric reports with diametrically opposed conclusions, it will in the end be up to the five Oslo district court judges to determine the thorny question of Breivik's sanity and his criminal responsibility when they hand down their verdict, probably around mid-July.