After confessing to the bombing and shooting spree, Breivik told his interrogators that he was a commander of a resistance movement aiming to overthrow European governments and replace them with "patriotic" regimes that would deport Muslim immigrants.
A pair of psychiatrists, on thirteen visits, spent 36 hours talking with Breivik. The doctors concluded that because Breivik was a paranoid schizophrenic, he was not a proper candidate for conviction and imprisonment as a criminal. As a result, prosecutors decided not to try Breivik for mass murder. Instead, he would be adjudicated insane and sent to a mental institution for an indeterminate period.
Under Norway's insanity defense doctrine, defendants who "lost touch with reality" are not considered criminals because their "crimes" are symptoms of the killer's mental illness. Breivik's victims, in other words, were killed by paranoid schizophrenia, not an evil, cold-blooded murderer.
Norwegian critics of the decision not to try Breivik as a criminal defendant called attention to Breivik's extensive planning and gruesome efficiency in the slaughter of his helpless victims. In the opinion of the Swedish forensic psychiatrist Anders Forsman, Breivik carried out his murderous mission in a rational way. He was, in Forsman's words, an "efficient killing machine."
In January 2012, under intense public pressure, the Oslo District Court ordered a second expert panel to evaluate Breivik's mental state at the time of the killings. In April 2012, the second psychiatric evaluation determined that Breivik possessed an antisocial personality disorder and narcissistic personality disorder. He was, in other words, not a psychotic who had lost touch with reality.
The Insanity Defense in the U.S.
Serial killers like Ted Bundy are rarely found not guilty by reason of insanity. The Unabomber Ted Kaczinsky, diagnosed as a paranoid schizophrenic, was convicted of murder in 1996 and sent to prison.
In the United States, jurors are not comfortable with finding mentally ill serial killers and mass murderers not guilty for any reason. They don't completely trust the social scientific findings of psychiatrists who testify for the defense. And jurors don't want to replace the concept of good and evil with sane and insane. Serial killers and mass murderers, to jurors, while obviously mentally unbalanced, are still evil and dangerous people. In America, evil people who murder are going to be punished criminally. That doesn't mean, however, that they don't receive some psychiatric treatment (drugs) in prison. But it does mean, whether medically "rehabilitated" or not, they are never going to be free.
John Hinckley, Jr. the man who shot President Ronald Reagan in 1981, was found not guilty by reason of insanity. This is because he was tried in federal court which applies a less demanding standard of legal insanity. In 2016, Hinckley was released permanently from the mental institution so he could live with or near his mother in Williamsburg, Virginia.