The present statutory test was signed into law as part of the Insanity Defense Reform Act of 1984 on October 12, 1984, and is applicable to offenses committed after that date. See United States v. Samuels, 801 F.2d 1052, 1054 n.1 (8th Cir. 1986) (Ex Post Facto Clause bars application of the new statutory test and burden of proof to prior acts). This standard, now codified at 18 U.S.C. § 17(a), formerly 18 U.S.C. § 20(a), provides as follows:
- AFFIRMATIVE DEFENSE - It is an affirmative defense under any Federal statute that, at the time of the commission of the acts constituting the offense, the defendant, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts. Mental disease or defect does not otherwise constitute a defense.
The current standard eliminates entirely the volitional prong of the cognitive/volitional test of the ALI Model Penal Code, the capacity to conform conduct to the requirements of the law. It also requires that the mental disease or defect be "severe." This concept was added as a committee amendment "to emphasize that non-psychotic behavior disorders or neurosis such as an "inadequate personality, immature personality, or a pattern of antisocial tendencies do not constitute the defense." See S.Rep. No. 225, 98th Cong., 1st Sess. 229, reprinted in 1984 U.S. Code Cong. & Admin. News 3182, 3411; United States v. White, 766 F.2d 22 (1st Cir. 1985). This standard was intended to incorporate the conclusion of the case law that voluntary use of alcohol and drugs, even if they render the defendant unable to appreciate the nature and quality of the act, does not constitute insanity or any other legally valid affirmative defense. Id.
The explicit provision that mental disease or defect does not otherwise constitute a defense is intended to ensure that the requirements of the standard are not circumvented in the guise of showing some other affirmative defense such as "diminished capacity." Id. This provision does not necessarily bar, however, the use of psychiatric testimony to negate specific intent, where specific intent is an element of the crime. See United States v. Cameron, 907 F.2d 1051, 1063-66 (11th Cir. 1990); United States v. Pohlot, 827 F.2d 889, 896-97 (3d Cir. 1987), cert. denied, 484 U.S. 1011 (1988); United States v. Gold, 661 F. Supp. 1127, 1128-31 (D.D.C. 1987).
[cited in USAM 9-18.000]