The insanity defense is an affirmative defense to criminal charges in the state of New York. When an Insanity or Defense of Lack of Criminal Responsibility is raised, the burden is not on the defendant to prove any lack of criminal responsibility.The Criminal Division is responsible for processing and managing all indictable criminal cases involving adult offenders. Mental Impairment Short of Insanity. This mental illness must satisfy the legal definition of insanity, which confirms that the defendant was at the time incapable of determining right from wrong. The following basic criteria must apply: • The Conviction must have occurred in Middlesex. County. What Happens If I Plead Insanity? What Happens if the Court Finds Me Insane? If you believe you are eligible for a Public Defender, you must fill out the required forms. In an insanity defense, the defendant admits the action but asserts a lack of culpability based on mental illness.