ALI Test Law and Legal Definition

ALI test is a test established by the American Law Institute Model Penal Code which provides that a defendant would not be criminally responsible for conduct if "as a result of mental disease or defect, he lacked substantial capacity either to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law." [United States v. Brown, 326 F.3d 1143, 1146 (10th Cir. 2003)].

In enacting the Insanity Defense Reform Act (IDRA) in 1984, Congress eliminated the volitional branch, which is the latter portion of the ALI test. The IDRA also "eliminated all other affirmative defenses or excuses based upon mental disease or defect." Therefore, the IDRA bars the introduction of evidence of a defendant's mental disease or defect to demonstrate that he lacked substantial capacity to control his actions or reflect upon the consequences or nature of his actions. [United States v. Brown, 326 F.3d 1143, 1146 (10th Cir. 2003)].

The ALI test received wide acceptance, and by 1982 all federal courts and a majority of state courts had adopted the ALI test. The test no longer applies at a federal level. While some states have dropped the ALI test, 18 states still use the ALI test in their definitions of insanity.