The insanity defense concerns the issue of the concept of insanity which defines the extent to which a person accused of crimes can be exonerated from criminal liability due to a mental illness. “The term insanity regularly attracts widespread public attention, which is far out of proportion to the impact of the defense on criminal justice” (Butler, 133). The decision of this defense is determined solely by the trial judge and jury. They determine if a criminal suffers from a mental illness. The final determination of mental illness rests solely with the jury using evidence and information gleaned from an expert witness. The result of such a determination places the accused individual either in a psychiatric facility, incarcerated, or freed from all charges. Due to the above factors, the insanity defense poses many problems. Some issues would be the actual possibility of determining mental illness, the justification for placing offenders deemed "mentally ill" and the total usefulness of such a defense. Overall, it is felt that the insanity defense should be invalid and unnecessary and should potentially be abolished altogether. Insanity is a legal definition, not a medical one. This makes mental illness and insanity correlated, only certain mental illnesses are considered inanity. Insanity includes not only mental illness, but also mental deficiencies. There are major problems with how exactly to apply medical theory to legal issues. Every crime involves a physical and mental act and the non-physical cause of the behavior. Mens rea is the mental element that would be required for a crime, if absent it exonerates the criminal from criminal responsibility...... in the middle of a paper...... or by making him take written tests. Some psychiatrists consider mental illness a myth. The insanity defense would require both mental illness and a connection between the illness and criminal behavior, neither of which could be scientifically proven. Among criminals acquitted and convicted using the insanity defense, many have presented compelling evidence of recidivism. Many dangerous people are allowed back on the streets and many non-dangerous people are forced into institutions due to an insanity plea, adding even more confusion and injustice within the justice systems and medical. The insanity defense is impossible to maintain on the basis of rules such as the M'Naghten rule, and the relationship between law and psychiatry must be reestablished at a more scientific level, based on ongoing neurological work in brain science..