Not guilty by reason of insanity means you don't have to be punished for your crimes - right?
Before we get to the issue of punishment though, let's make sure we have a firm grasp of what the Not Guilty by Reason of Insanity plea (NGRI) is.
The NGRI is a unique plea not only because it references mental illness, but because it is saying something seeming paradoxical - the individual has committed a guilty act without having a guilty mind.
What? We watch law and order and time and time again it's about proving that it was Joe that killed Mary. So if there's no question there, then what are they talking about? What's this "guilty mind" nonsense?
Well, lets talk about insanity. Insanity, despite the way we throw it around everyday, actually has a stringent legal definition. It is a "mental illness of such a severe nature that a person cannot
distinguish fantasy from reality, cannot conduct her/his affairs due to
psychosis, or is subject to uncontrollable impulsive behavior. Insanity
is distinguished from low intelligence or mental deficiency due to age
or injury." (http://legal-dictionary.thefreedictionary.com/insanity)
The crux of this definition is the severity of the mental illness. Even if a person is in the midst of a psychotic break it is extremely unusual for them to be so completely impaired that they they think they are holding a banana when they are actually holding a gun. Another example of a severe mental illness is if the individual was so out of touch with reality - so utterly in the throws of a delusion, for example, that they honestly believe that if they don't kill their son then he will be tortured in hell for all of eternity. So they kill their son.
The NGRI, then, is not a trial whose goal is to determine whether the individual committed a crime, rather it will be based on "the issue of the defendant's insanity (or sanity) at
the time the crime was committed." (http://legal-dictionary.thefreedictionary.com/insanity)
So let's skip to the end, let's say that an individual actually goes through a trial, and the verdict is Not Guilty by Reason of Insanity. (Which less than 10% of individuals who attempt this plea succeed in doing). Does the individual go free?
By no means. The individual goes to a state mental hospital until they can prove that they are no longer a threat to society due to their mental illness.
This means that the individual may actually spend more time locked away from society than they would have in jail.
A infamous example of this is John Hinckley, Jr. - the man that attempted to kill then-President Ronald Regan in order to win the love of teen actress Jodie Foster. His conviction was not guilty by reason of insanity.
He is still in St. Elizabeth's Hospital in Washington, DC. He has been there more than thirty years.