Legal and moral responsibility are both present when a 'true crime' is committed. A 'true crime' includes both the physical act or an omission of an act in violation of a law ('actus reus') and the mental element or criminal intent ('mens rea'). The state is justified in punishing persons who commit 'true crimes,' because they are both legally and morally responsible for the crime. Of central concern in establishing mens rea is the extent to which the accused had control over his/her conduct at the time the crime occurred. Persons considered to be legally not responsible for an act prohibited by law are children under the age of 7 and those suffering from a mental defect that prevents them from having sufficient capacity-responsibility. In determining whether an accused has sufficient mental disability to be held not morally responsible for the charged behavior, State and Federal jurisdictions rely on 19 variations of the four basic insanity defenses: the M'Naghten test, the irresistible impulse tests, the Durham rule, and the substantial capacity test. Although problems resulting from the amalgam of law and psychiatry and problems inherent in the insanity tests themselves have brought criticism of the insanity defense, suggestions to abolish it or radically revise it would permit the state to punish persons whose mental states are such that they cannot be considered morally responsible for their behavior. This would be unjust and possibly unconstitutional. Vagueness and ambiguity may be necessary components of any insanity test until reliable and valid empirical tests of responsibility can be devised, and persons whose past behavior indicates they are dangerous, regardless of their mental state, should be incapacitated and treated, with incapacitation diminishing as those previously not morally responsible for their behavior become more responsible. Fifty-three notes are provided.