If someone is schizophrenic or mentally disabled and doesnt understand what they are doing they should not get the same sentence as someone who is in their right mind. If soneone isnt their senence should be more rehab based than someone who is in their right mind. Im not saying let them walk free im saying have a conscience and dont let our justice system be run by irrational emotion and knee jerk reactions.
There are some people who really are legitimately insane and should be treated at a mental institution and if they can be cured sufficiently released with some restrictions like having to regularly see a psychiatrist depending on the condition they are released in.
I do think that the insanity defense is often abused though. It should be strictly limited to cases where had the insane person's delusions been correct then that itself would've been a defense to the crime. So for instance a person who kills because he delusionally believes he must in order to save the world should be considered "not guilty by reason of insanity" since had he not been delusional and the world really had been in danger that would've almost certainly been accepted as a defense.
BUT for example a person who delusionally believes that by committing murder they will impress a famous celebrity should NOT get "not guilty by reason of insanity." Perhaps it would be appropriate to send them to a mental institution to be treated for their illness at first but upon being cured they should be transported to prison to serve out their sentence. But considering them "not guilty" would be wrong because had their delusion been correct it could not even remotely be argued that this would be accepted by the court as a defense. In other words if the celebrity really would've been impressed the person would be found guilty, so they should be considered just as guilty if a mental illness makes them think the celebrity would be impressed. Either way they should've decided that their crime was not worth impressing a celebrity.
A person who commits a crime based on a delusion of which had it been true would've still been no excuse is not safe to reenter society just because their mental illness is cured. They have still shown they are willing to commit a crime under circumstances that do NOT justify it.
As humans, we have an ability to understand the role of intent in crime, which is reflected in our legislation. Possibly the most widely known example of this is the distinction between murder and manslaughter. In western societies, most judicial systems apply stronger punishments to people who premeditate the act of killing someone than someone who does it in the heat of the moment. Either way, the person dies and their family cannot 'get them back' no matter what the killer's intent was.
For the same reason, a mentally ill person who commits a crime without the intention or understanding of their crime should not be treated in the same way as a person who committed the crime freely. A mental illness is effectively like a lack of free will or ability to choose, as it alters someone's perspective and means that they cannot make an accurate, informed decision, and prosecuting people who do not have a freely created intention to commit a crime in the same way as people who do ignores the multifaceted, layered nature of our actions and our justice system.
Insanity pleas should not be allowed as this basically allows the defendant to be set free without any punishment whatsoever. A potentially violent person is released as a result of the plea; what if someone else is hurt by their actions? Instead of stating that someone is innocent because of insanity, the crime should be acknowledged and they should be marked guilty if it is found that they truly committed the crime. An insane criminal should be put into solitary confinement so that they may be able to recieve help (or forced to, really) while kept in confinement to keep the public safe. In some cases, these type of people are released and told by the court to seek help. However, because of HIPPA and other necessary laws, they can avoid going to their assigned clinic and seeking treatment.
Though I do agree with most of MasturDbtor's argument, a wrong has been committed and the victims are also in need of consideration. Even if the insane kills in order to "save the world", they've killed. No good deed goes unpunished, and considering the magnitude of the "means" to reach that "end" it should be accepted to sacrifice the self just in case they were wrong.
This is hardly the logic of a madman, but to believe killing a person for some greater good should not be punished is inviting more people to do the same.