It looks like Breivik's lawyer is already arguing that his client is insane. Considering the "knight" persona that Breivik built up for himself, it's a defense that might actually work, provided any supporting evidence goes beyond the 76 lives lost in tugging at the jury's hearts. One thing I will say, though, is that for someone supposedly disconnected from reality, Breivik was awfully articulate in detailing his deception strategy within his manifesto.
Also, it appears that Norway's intelligence agency [URL=http://www.telegraph.co.uk/news/worldnews/europe/norway/8661084/Norway-killer-Anders-Behring-Breivik-came-to-attention-of-intelligence-services-in-March.html]did have an eye on Breivik... they just didn't act aggressively enough to prevent this tragedy. I guess he wasn't completely under the radar after all. It's a pity that being noticed wasn't enough to derail his plans....