Yes. Absolutely it is.
A large part of the reason why we punish criminal behaviour is because of the guilty mind. You are a sane, free-thinking individual who knows societies laws and knows the difference between right and wrong, and you chose either to flout those laws, or to simply not even care about the laws and/or the people affected by your action. You made that decision of your own free will, and because it was a free choice we see fit to punish you for committing your mind to such an action.
If you are a sane, rational person, and you choose to disregard sanity and rational thought because you are angry, or for any other such reasons, then we see fit to punish you, because you chose that course of action, or committed yourself to a way of thinking that society considers wrong, destructive, and makes you a dangerous person who will probably re-offend. If you make a choice to do something in a certain state of mind, and you are sane when you do so, we have every reason to believe you will make that same decision again if put in a similar situation.
Now, when someone has a mental illness, punishing people becomes a lot more problematic, because that person's actions were not necessarily any kind of free choice. If you are in, say, a state of psychosis where you have blacked out, you were not in control of any of your actions at that time, although your body was committing them. Moreover, it is likely that the reprehensible act or action would not have occurred if you had been given a free choice in a sane state of mind. If you were put in the same situation, but we remove the mental illness or have that same person in a sane state of mind, we have no way of knowing whether they would have made the same decision. We have to assume that person would be innocent or would make the legally condoned decision if they had been acting under their own free will and control at the time.
Thus, it does more benefit to society to attempt to cure people of that mental state. If you have someone who is a completely good member of society, who is kind, friendly, loving, and who works hard, and contributes to their community, but who happens to have a mental disorder beyond their control, and who happens to commit a crime during an episode of that mental illness and not while in a period of sanity, does it not on some level follow that we cannot hold the 'sane' aspect of that person accountable to exactly the same degree as a sane person (or themselves in a sane state) due to the intervening circumstance of a factor beyond their control? Or to put it in really simplistic terms, should the 'sane' side of the personality be punished for the actions of an insane other half who is not the same person at all? We don't hold both sides of conjoined twins accountable for a crime if only one twin committed it, do we?
Really, saying that the insanity plea isn't a legitimate defence at all kind of opens up the door for a lot of exploitation of a lot of people, and not just in the area of criminal law. It's a bit like saying that if you take an insane person off their medications and then get them to sign their life savings over to you, that signature should count, even though in their rational state of mind they would never have made that decision at all.
It's not like we just set these people free to pose a danger to the community, mind you. Arguably, people who plead insanity serve longer 'sentences' on average than sane people who commit crimes, because a successful insanity defence gets you committed to an institution indefinitely, until such a time as you pose no threat whatsoever. Meanwhile, if you send an insane person to jail, there's no guarantee that that environment and lack of sufficient treatment won't make them more violent and more dangerous when they're ultimately freed, which they will be, because, in my country and in Norway, we have maximum sentences. This means that they will definitely get out at some point, providing they don't die in prison.
Now, whether I actually think Anders Breivik is insane is a completely different matter. I am not commenting on Breivik at all here. Nothing I've said is about his case, and I'm not saying that I think it's entirely defensible in his situation. I don't know enough about him or his case to comment.
What's more important, however, is that you don't let one guy using this defence motivate you to take away the rights of an entire class of people who legitimately need this defence. Just because one person uses the defence in a manner you find appalling is not a just reason to advocate taking away the defence entirely. That's like asking whether self-defence is a legitimate defence or whether it should be taken away purely because people can lie about it or because it has been misused in the past and gotten some people off when it shouldn't have.
There is no need to capriciously punish people who actually need that defence all so we can be extra harsh and punitive to this one guy we really hate and want to see get what he deserves. That is entirely the wrong reason to take away people's rights.
A large part of the reason why we punish criminal behaviour is because of the guilty mind. You are a sane, free-thinking individual who knows societies laws and knows the difference between right and wrong, and you chose either to flout those laws, or to simply not even care about the laws and/or the people affected by your action. You made that decision of your own free will, and because it was a free choice we see fit to punish you for committing your mind to such an action.
If you are a sane, rational person, and you choose to disregard sanity and rational thought because you are angry, or for any other such reasons, then we see fit to punish you, because you chose that course of action, or committed yourself to a way of thinking that society considers wrong, destructive, and makes you a dangerous person who will probably re-offend. If you make a choice to do something in a certain state of mind, and you are sane when you do so, we have every reason to believe you will make that same decision again if put in a similar situation.
Now, when someone has a mental illness, punishing people becomes a lot more problematic, because that person's actions were not necessarily any kind of free choice. If you are in, say, a state of psychosis where you have blacked out, you were not in control of any of your actions at that time, although your body was committing them. Moreover, it is likely that the reprehensible act or action would not have occurred if you had been given a free choice in a sane state of mind. If you were put in the same situation, but we remove the mental illness or have that same person in a sane state of mind, we have no way of knowing whether they would have made the same decision. We have to assume that person would be innocent or would make the legally condoned decision if they had been acting under their own free will and control at the time.
Thus, it does more benefit to society to attempt to cure people of that mental state. If you have someone who is a completely good member of society, who is kind, friendly, loving, and who works hard, and contributes to their community, but who happens to have a mental disorder beyond their control, and who happens to commit a crime during an episode of that mental illness and not while in a period of sanity, does it not on some level follow that we cannot hold the 'sane' aspect of that person accountable to exactly the same degree as a sane person (or themselves in a sane state) due to the intervening circumstance of a factor beyond their control? Or to put it in really simplistic terms, should the 'sane' side of the personality be punished for the actions of an insane other half who is not the same person at all? We don't hold both sides of conjoined twins accountable for a crime if only one twin committed it, do we?
Really, saying that the insanity plea isn't a legitimate defence at all kind of opens up the door for a lot of exploitation of a lot of people, and not just in the area of criminal law. It's a bit like saying that if you take an insane person off their medications and then get them to sign their life savings over to you, that signature should count, even though in their rational state of mind they would never have made that decision at all.
It's not like we just set these people free to pose a danger to the community, mind you. Arguably, people who plead insanity serve longer 'sentences' on average than sane people who commit crimes, because a successful insanity defence gets you committed to an institution indefinitely, until such a time as you pose no threat whatsoever. Meanwhile, if you send an insane person to jail, there's no guarantee that that environment and lack of sufficient treatment won't make them more violent and more dangerous when they're ultimately freed, which they will be, because, in my country and in Norway, we have maximum sentences. This means that they will definitely get out at some point, providing they don't die in prison.
Now, whether I actually think Anders Breivik is insane is a completely different matter. I am not commenting on Breivik at all here. Nothing I've said is about his case, and I'm not saying that I think it's entirely defensible in his situation. I don't know enough about him or his case to comment.
What's more important, however, is that you don't let one guy using this defence motivate you to take away the rights of an entire class of people who legitimately need this defence. Just because one person uses the defence in a manner you find appalling is not a just reason to advocate taking away the defence entirely. That's like asking whether self-defence is a legitimate defence or whether it should be taken away purely because people can lie about it or because it has been misused in the past and gotten some people off when it shouldn't have.
There is no need to capriciously punish people who actually need that defence all so we can be extra harsh and punitive to this one guy we really hate and want to see get what he deserves. That is entirely the wrong reason to take away people's rights.