Clark v. Arizona
548 U.S. 735 (2006)

  • Clark killed a policeman. He was arrested and charged with first-degree murder.
    • First-degree murder requires that the defendant intentionally or knowingly killed the victim.
  • At Trial Clark argued that he was insane as was under the delusion that aliens were impersonating government officials.
    • Clark argued that his inability to understand the nature of his acts at the time they were committed should be a sufficient basis for an insanity defense.
      • Basically, Clark was saying that he should be allowed to claim that his insanity prohibited him from forming intent (aka mens rea), and so he could not be found guilty of a crime that requires intent.
  • The Trial Court found Clark guilty of first-degree murder. He appealed.
    • The Trial Court found that, although Clark was crazy, his schizophrenia did not prevent him from knowing right from wrong, therefore he could not claim insanity as a defense.
      • Basically, even though Clark thought the policeman was an alien, he was still competent enough to know that shooting him would result in death, and that killing someone was a crime.
    • Arizona only allows an insanity defense if a defendant is unable to tell right from wrong.
  • The Appellate Court upheld the conviction. Clark appealed.
    • The Arizona Supreme Court denied cert.
  • The US Supreme Court upheld the conviction.
    • The US Supreme Court found that it is not a violation of due process to have an insanity test stated solely in terms of the capacity to tell whether an act charged as a crime was right or wrong.
      • Arizona could also constitutionally limit a defendant’s evidence of mental defect to only what is relevant to that insanity test, even when mens rea is an element of the charged crime.
  • Most States do not impose a restriction on the use of mental health evidence to rebut a requirement of mens rea, but several (including Arizona) due. This decision said that restriction is not a violation of due process.
    • Some States (like California), have a partial restriction, where the evidence can be used to rebut intent only in crimes that involve a specific intent, not those that require only a general intent.