In most cases, you still end up in the joint to my knowledge.

Would also take the death penalty off the table I imagine.

Everytime I read the thread title I get the song Hungry Eyes in my head.

Not guilty by reason of insanity doesn't mean "not guilty". The legal defiinition for it is, as I understand it, that the person was unable to understand that what they were doing was wrong. Not just didn't understand, but couldn't.

An important distinction to be made is the difference between competency and criminal responsibility.

The issue of competency is whether a defendant is able to adequately assist his attorney in preparing a defense, make informed decisions about trial strategy and whether or not to plead guilty or accept a plea agreement. This issue is dealt with in UK law as "fitness to plead"[citation needed].

Competency largely deals with the defendant's present condition, while criminal responsibility addresses the condition at the time the crime was committed[citation needed].

In the United States, a trial in which the insanity defense is invoked typically involves the testimony of psychiatrists or psychologists who will, as expert witnesses, present opinions on the defendant's state of mind at the time of the offense.

Therefore, a person whose mental disorder is not in dispute is determined to be sane if the court decides that despite a "mental illness" the defendant was responsible for the acts committed and will be treated in court as a normal defendant. If the person has a mental illness and it is determined that the mental illness interfered with the person's ability to determine right from wrong (and other associated criteria a jurisdiction may have) and if the person is willing to plead guilty or is proven guilty in a court of law, some jurisdictions have an alternative option known as either a Guilty but Mentally Ill (GBMI) or a Guilty but Insane verdict. The GBMI verdict is available as an alternative to, rather than in lieu of, a "not guilty by reason of insanity" verdict.[13] Michigan (1975) was the first state to create a GBMI verdict, after two prisoners released after being found NGRI committed violent crimes within a year of release, one raping two women and the other killing his wife.[14]

I had a high school teacher many years ago who said, "I'm sorry, but if you murder someone, you're insane. That's not a defense."

Not sure I agree, but it's always made me think in cases like this.