Jaydee wrote:
He's sentenced to 21 years of preventive detention. This means that he will never get out as long as he is regarded as dangerous. If he never regrets his actions, never admits to the horrors he's caused, and never admits to understanding the pain and suffering he's caused, he will not get out of prison. It's life imprisonment in practice.
If a convict shows no signs of improvement (this has to be documented) in prison in Norway, he can be kept there for life. I somehow doubt that they'll ever see any improvement in Anders Behring Breivik.
Furthermore, he'll be kept completely isolated from the other prisoners and won't have any significant social contact for the rest of his life. Many other convicts who feel bad about what they've done may feel that they set things straight again and cancel out their bad deeds if they kill Breivik.