Dissident psychiatrists have rejected the notion of a purely mental disease as inherently tainted with moral, nonmedical judgments and regard a person as insane only if damage to the brain or its functioning can be demonstrated. This identification of mental disease with brain disease is unwarranted and fails to consider the legal notions of intent, responsibility, culpability, and blameworthiness. Mental disease should be legally relevant only when it demonstrably interferes with the ability of an actor to direct his actions so as to avoid legal liabilities. With any of the following psychological conditions an individual cannot be held responsible for his actions and can raise the insanity defense: blackouts, convulsions, somnambulism, and possibly hypnotic states; insanity; and inability to conform to the law. The defendant should bear the burden of demonstrating insanity. Courts should try the sane and the insane alike, but entertain an insanity defense only after the defendant has been found to have done what he was charged with. If the court feels a recurrence of a dangerous state is likely, it may be empowered to impose precautionary measures varying from medical treatment to civil commitment. Defendants found to be dangerous should be confined to an institution for the insane for a period no less than the minimum sentence that would have been imposed had they been sane. Courts should hear no more than three psychiatric witnesses in an insanity defense case. Decisions regarding the place and length of confinement of persons found guilty as charged but insane should be left to the courts rather than psychiatrists. The paper contains 14 footnotes.