Lexis Nexis - Case Brief

Not a Lexis Advance subscriber? Try it out for free.

Law School Case Brief

Clark v. Arizona - 548 U.S. 735, 126 S. Ct. 2709 (2006)


The United States Supreme Court reads the Arizona Supreme Court's Mott restriction refusing to allow psychiatric testimony to negate specific intent to apply to evidence addressing the two issues in testimony that characteristically comes only from psychologists or psychiatrists qualified to give opinions as expert witnesses: mental-disease evidence (whether at the time of the crime a defendant suffered from a mental disease or defect, such as schizophrenia) and capacity evidence (whether the disease or defect left him incapable of performing or experiencing a mental process defined as necessary for sanity such as appreciating the nature and quality of his act and knowing that it was wrong). The Arizona Supreme Court was careful to distinguish this kind of opinion evidence from observation evidence generally and even from observation evidence that an expert witness might offer, such as descriptions of a defendant's tendency to think in a certain way or his behavioral characteristics; the Arizona court made it clear that this sort of testimony was perfectly admissible to rebut the prosecution's evidence of mens rea. Thus, only opinion testimony going to mental defect or disease, and its effect on the cognitive or moral capacities on which sanity depends under the Arizona rule, is restricted. 


Defendant, a driver, shot and killed a police officer conducting a traffic stop. Initially defendant was found incompetent to stand trial and was committed to a state hospital for treatment, but two years later the same trial court found his competence restored and ordered him to be tried. At trial, defendant did not contest the shooting and death, but relied on his undisputed paranoid schizophrenia at the time of the incident in denying that he had the specific intent to shoot a law enforcement officer or knowledge that he was doing so, as required by Ariz. Rev. Stat. § 13-1105(A)(3). Defendant challenged a 1993 amendment to Arizona's insanity rule, Ariz. Rev. Stat. § 13-502(A), excising the express reference to the cognitive incapacity element of the M'Naghten test. The trial court ruled that defendant could not rely on evidence bearing on insanity to dispute the mens rea required for first-degree murder.On appeal, the Court of Appeals of Arizona affirmed the trial court.


Does due process prohibit Arizona from narrowing its insanity test or from excluding evidence of mental illness and incapacity due to mental illness to rebut evidence of the requisite criminal intent?




The Court held that history showed no deference to M'Naghten that could elevate its formula to the level of fundamental principle, so as to limit the traditional recognition of a State's capacity to define crimes and defenses. Because allowing mental-disease evidence on mens rea could easily mislead, it was not unreasonable to confine consideration of that kind of evidence to the insanity defense.

Access the full text case Not a Lexis Advance subscriber? Try it out for free.
Be Sure You're Prepared for Class