The right-wing fanatic behind a bomb-and-shooting massacre that killed 77 people in Norway admitted to the “acts” on Monday but pleaded not guilty to criminal charges, saying he was acting in self-defence.

Anders Behring Breivik defiantly rejected the authority of the court as he went on trial for the July 22 attacks that shocked the peaceful nation and jolted the image of terrorism in Europe.

Dressed in a dark suit and sporting a thin beard along his jawline, Mr. Breivik smiled as a guard removed his handcuffs in the crowded courtroom. “I don’t recognise Norwegian courts because you get your mandate from the Norwegian political parties, who support multiculturalism,” Mr. Breivik said in his first comments to the court.

“I admit to the acts, but not criminal guilt,” he told the court, and said he had acted in self-defence.

Mr. Breivik also said he doesn’t recognise the authority of Judge Wenche Elisabeth Arntzen, because he said she is friends with the sister of former Norwegian Prime Minister and Labour Party leader Gro Harlem Brundtland.

While there is a principle of preventive self-defence in Norwegian law, it doesn’t apply to Mr. Breivik’s case, said Jarl Borgvin Doerre, a legal expert, who has written a book about the concept.

“It is obvious that it has nothing to do with preventive self-defence,” Mr. Doerre told AP.

The key issue to be resolved during the 10-week trial is the state of Breivik’s mental health, which will decide whether he is sent to prison or to psychiatric care.

If deemed mentally competent, he would face a maximum prison sentence of 21 years or an alternate custody arrangement under, which the sentence is prolonged for as long as an inmate is deemed a danger to society.

Police sealed off the streets around the court building, where journalists, survivors and relatives of victims watched the proceedings in a 200-seat courtroom built specifically for the trial.

Thick glass partitions were put up to separate the defendant from victims and their families, many of whom are worried that Mr. Breivik will use the trial to promote his extremist political ideology. In a manifesto he published online before the attacks, Mr. Breivik wrote that “patriotic resistance fighters” should use trials “as a platform to further our cause.”

Norway’s NRK television will broadcast parts of the trial, but it is not allowed to show Mr. Breivik’s testimony.

Mr. Breivik surrendered to police 1 hour and 20 minutes after he arrived on Utoya. The police response was slowed by a series of mishaps, including the lack of an operating police helicopter and the breakdown of an overloaded boat carrying a commando team to the island.

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