Opinion ID: 1925880
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Heading: Delaware History of Mental Illness as a Defense

Text: At common law, Delaware recognized two categories of mental illness as discharging a defendant from criminal responsibility for his actions. First, under the common law, if the defendant did not know the nature and quality of his acts or did not know that such acts were wrong due to a mental illness, a defendant could be found not guilty by reason of insanity. This concept has been recognized in many jurisdictions since the seminal decision in M'Naghten's Case, 8 Eng.Rep. 718 (H.L.1843). It is generally referred to as the right-wrong test of responsibility for crime. See Mills v. State, Del.Supr., 256 A.2d 752, 756 (1969); Longoria v. State, Del.Supr., 168 A.2d 695, 700-02, appeal dismissed, 368 U.S. 10, 82 S.Ct. 18, 7 L.Ed.2d 18 (1961). In addition to the right-wrong test, the Delaware common law also recognized irresistible impulse as a defense to criminal liability. Under that concept, if the defendant was able to convince the trier of fact of his inability to control his behavior due to an irresistible impulse, he could be found not guilty by reason of mental illness. See Longoria v. State, 168 A.2d at 701-02. In 1973, the Delaware legislature enacted a comprehensive criminal code in which the irresistible impulse and right-wrong defenses of mental illness or mental defect were codified. [3] The Delaware Code provided that: In any prosecution for an offense, it is an affirmative defense that, at the time of the conduct charged, as a result of mental illness or mental defect, the accused lacked substantial capacity to appreciate the wrongfulness of his conduct or lacked sufficient willpower to choose whether he would do the act or refrain from doing it. 11 Del.C. § 401(a) (1979) (amended 1982). In July of 1982, 11 Del.C. § 401 was substantially amended. The amended statute retained the defense of insanity where a defendant lacked substantial capacity to appreciate the wrongfulness of his conduct, i.e., the right-wrong test. However, the legislature eliminated as a defense the situation in which a defendant, due to a mental illness or mental defect, committed an act but lacked sufficient willpower to choose whether he would do the act or refrain from doing it, i.e., the irresistible impulse test. In the latter context, the amended statute provided for a defendant to be found guilty but mentally ill. Section 401 now provides in pertinent part as follows: (a) In any prosecution for an offense, it is an affirmative defense that, at the time of the conduct charged, as a result of mental illness or mental defect, the accused lacked substantial capacity to appreciate the wrongfulness of his conduct. If the defendant prevails in establishing the affirmative defense provided in this subsection, the trier of fact shall return a verdict of not guilty by reason of insanity. (b) Where the trier of fact determines that, at the time of the conduct charged, a defendant suffered from a psychiatric disorder which substantially disturbed such person's thinking, feeling or behavior and/or that such psychiatric disorder left such person with insufficient willpower to choose whether he would do the act or refrain from doing it, although physically capable, the trier of fact shall return a verdict of guilty, but mentally ill. . . . . 11 Del.C. § 401 (1987).