Clark v. Arizona (2006)

United States Supreme Court

548 U.S. 735

Nature of Case

Whether it is unconstitutional to narrow the insanity test to include only moral capacity and whether it is unconstitutional to exclude evidence of mental illness which could help to negate mens rea.

Facts of Case

Police received complaints of an individual driving a pickup truck and blaring loud music in the early hours of June 21, 2000. Officer Moritz stopped the driver, 17-year-old Eric Michael Clark. Clark shot the officer and the police officer died soon after, but was able to call for help first. Clark ran away on foot, but was arrested later that day with gunpowder residue on his hands and the gun that killed the officer nearby. Clark was charged with first-degree murder (acted intentionally or knowingly). He was found incompetent to stand trial in March, 2001, but two years later was found restored to competence. Clark waived his right to a jury. At the bench trial Clark did not contest the shooting, but denied that he had the specific intent required by the statute, because of his mental disorder (Schizophrenia, Paranoid Type). He raised the affirmative insanity defense and had to prove by a clear and convincing standard that “at the time of the commission of the criminal act he was afflicted with a mental disease or defect of such severity that he did not know the criminal act was wrong.” He also attempted to introduce evidence of mental disorder to negate the requisite mens rea for specific intent. The court did not allow him to introduce evidence to negate specific intent and held “Arizona does not allow evidence of a defendant’s mental disorder short of insanity…to negate the mens rea element of a crime.

At his trial, Clark presented testimony from classmates, school officials, and his family describing his bizarre behavior over the past year. His behavior included keeping a bird in his car to warn of airborne poison, and he had a fishing line with chimes to alert of intruders into his home. Clark also held a belief that Flagstaff, Arizona was populated with aliens (disguised as government officials) who were trying to kill him and bullets were the only mechanism to stop them. Mr. Clark’s schizophrenia diagnosis was undisputed and all experts agreed that he was psychotic at the time of the crime; however, the judge found that at the time of the crime his mental illness “did not distort his perception of reality so severely that he did not know his actions were wrong.” He found Clark guilty of first-degree murder and he was sentenced to life imprisonment without the possibility of release for 25 years.

Clark moved to vacate the judgment and sentence arguing that the insanity standard and the Mott rule violated due process. He argued that the 1993 narrowing of the insanity standard was unconstitutional, because it eliminated the first part of the M’Naghten test (“as not to know the nature and quality of the act he was doing”). Clark argued that the elimination of this component “offends [a] principle so rooted in the traditions and conscience of our people as to be ranked fundamental.” The Court of Appeals affirmed Clark’s conviction and held that the insanity standard did not violate due process, because there is no constitutional requirement to even recognize an insanity defense. The appellate court also believed Mott barred the trial court from considered evidence of mental illness to negate mens rea and they denied further review. The United States Supreme Court granted certiorari to review whether Arizona’s narrow insanity test and Mott rule violated 14th Amendment due process rights.


Did the Court of Appeals for Arizona err in affirming the defendant’s conviction, in allowing a narrow test of insanity, and in excluding evidence of a mental illness that could have been used to rebut evidence of specific intent?



In a 6 to 3 decision, in an opinion delivered by Justice Souter, the Court affirmed the judgment of the Court of Appeals for Arizona. The Court held that the 14th Amendment was not violated by a narrowly defined insanity test (moral capacity to tell whether the act was right or wrong), or by limiting consideration of mental illness strictly to its bearing on insanity (Mott rule).


The Court concluded that due process was not violated, because history showed no “deference to M’Naghten that could elevate its formula to the level of a fundamental principle, so as to limit the traditional recognition of a State’s capacity to define crimes and defenses.” Additionally, the Court found that the Mott rule did not violate due process, because, the prosecution must prove the defendant committed the crime and did so knowingly or intentionally, beyond a reasonable doubt. Therefore, if Arizona wanted to limit consideration of mental illness and capacity to bear on insanity only, it did not violate the defendant’s due process rights. The Court further stated, “because allowing mental-disease evidence on mens rea can thus easily mislead, it is not unreasonable to address that tendency by confining consideration of this kind of evidence to insanity, on which a defendant may be assigned the burden of persuasion.”