“Go to hell, go to hell, you killed my brother,” the man screamed from the second row of the public gallery as he hurled the shoe at Breivik a few metres (yards) away, newspaper VG reported on its website.
The shoe missed Breivik but struck his co-defence lawyer, Vibeke Hein Baera, who was seated closest to the public gallery, during the presentation of an autopsy report.
Police described the thrower as the brother of one of Breivik’s victims, but the man’s name was not immediately available.
Some in the courtroom applauded, or uttered the word “finally”, and others started to cry. The shoe thrower was removed by police. Police numbers were boosted in the court after the incident.
“If anyone wants to throw something, you can throw at me when I’m entering or leaving the court,” Breivik was quoted by local media as saying after the incident.
“Don’t throw things at my lawyers.”
The incident came during a week of harrowing testimony from survivors of Breivik’s gun rampage across the small island of Utoeya last July, where the ruling Labour Party was holding a youth camp. He killed 69 people there, many of them teenagers.
“We regard this as a spontaneous emotional outburst that happened in the courtroom,” Rune Bjoersvik, the police officer charge of police operations in the court, told Reuters.
“He (the shoe-thrower) was in court and he had prepared emotionally to be there, but the emotions took over, which is understandable. We wish it hadn’t happened, but we don’t regard this a dramatic breach of safety.”
Breivik has listened calmly to the descriptions of his killings and shown little emotion, except when hearing descriptions about how he was said to have let out “cries of joy” and laughed while shooting, which he has denied.
He has admitted the killings, but denies criminal responsibility. He says he was defending Norwegian ethnic purity from Muslim immigration and the multiculturalism backed by the Labour Party.
Breivik has said he felt he had no choice but to strike back, bombing government offices in an attack that killed eight people and then carrying out the massacre at the Labour Party island summer camp.
During Friday’s hearing, Breivik said one person at Utoeya had attacked him during his rampage, throwing an object at his face, but gave no more details.
Ahead of the trial, one court-appointed team of psychiatrists concluded that Breivik was psychotic, while a second found him mentally capable.
Breivik has said he should either be executed or acquitted, calling the prospect of a prison sentence “pathetic” and an insanity ruling “worse than death”.
If he is deemed sane, he could face a 21-year prison sentence with indefinite extensions for as long as he is considered dangerous.