In the U.S., prosecutors often challenge any insanity plea regardless of its obvious strength — ignoring their obligation to seek justice as opposed to the maximum level of punishment or sentencing.
Breivik is a self-described anti-Muslim militant and has shown bizarre behavior throughout the trial. He claims Norway and Europe are being colonized by Muslims. I have little doubt that prosecutors in U.S. would have pushed for sanity and the death penalty in such a case — helped by an insanity standard in the United States that ignores generally recognized definitions of mental illness. Under that standard, prosecutors would simply argue that he could still tell the difference between right and wrong and seek the death penalty.
Norway clearly draws the line with greater care and its prosecutors are willing to face public backlash to do what they believe is justice in such cases. While they may also believe that he could be held longer in an asylum, it is clear that the Norwegian legal school applies a more scrutinizing process for such claims.
Source: BBC
