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The Substantial Capacity Test

5 October, 2015 - 14:16

The substantial capacity test is the insanity defense created by the Model Penal Code. The Model Penal Code was completed in 1962. By 1980, approximately half of the states and the federal government adopted the substantial capacity test (also called theModel Penal Code or ALI defense). 1 However, in 1982, John Hinckley successfully claimed insanity using the substantial capacity test in his federal trial for the attempted murder of then- President Ronald Reagan. Public indignation at this not-guilty verdict caused many states and the federal government to switcfrom the substantial capacity test to the more inflexible M’Naghten standard. 2 In addition, jurisdictions that switched to M’Naghten also shifted the burden of proving insanity to the defendant. 3 The defendant’s burden of proof for the insanity defense is discussed shortly.

The substantial capacity test is as follows: “A person is not responsible for criminal conduct if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law” (Model Penal Code § 4.01(1)). The defense has two elements. The first element requires the defendant to have a mental disease or defect, like the M’Naghten and irresistible impulse insanity defenses. The second element combines the cognitive standard with volitional, like the irresistible impulse insanity defense supplementing the M’Naghten insanity defense. In general, it is easier to establish insanity under the substantial capacity test because both the cognitive and volitional requirements are scaled down to more flexible standards. Unlike the M’Naghten insanity defense, the substantial capacity test relaxes the requirement for complete inability to understand or know the difference between right and wrong. Instead, the defendant must lack substantial, not total, capacity. The “wrong” in the substantial capacity test is “criminality,” which is a legalrather than moral wrong. In addition, unlike the irresistible impulse insanity defense, the defendant must lack substantial, not total, ability to conform conduct to the requirements of the law. Another difference in the substantial capacity test is the use of the word “appreciate” rather than “know.” As stated previously, appreciate incorporates an emotional quality, which means that evidence of the defendant’s character or personality is relevant and most likely admissible to support the defense.