State of New Jersey v. Jeremy Arrington

Summary

The Supreme Court of New Jersey considers whether a defendant may assert an insanity defense without supporting expert testimony. The Court holds that expert testimony is required because determining the existence and effects of a mental disease is beyond the common experience of jurors. The Court affirms the judgment of the Appellate Division and concludes that the trial court properly declined to instruct the jury on insanity based solely on the defendant’s proposed lay testimony.

Holdings

1. A defendant must proffer qualified expert testimony to assert an insanity defense under N.J.S.A. 2C:4-1. The expert must credibly diagnose a disease of the mind and explain its impact on the defendant's behavior and reasoning at the time of the offense.
2. Requiring expert testimony to support an insanity defense does not violate a defendant's federal or New Jersey constitutional right to present a complete defense because the right to present a defense is subject to competent and reliable evidentiary rules and the trial court's gatekeeping function.
3. Even apart from the categorical expert-testimony rule, Arrington's proposed evidence was insufficient to raise the insanity defense because it consisted essentially of his own self-serving testimony and the gruesome nature of the crimes, neither of which established a disease of the mind or its contemporaneous effect on his reasoning.

Questions Presented

1. Whether a criminal defendant may assert a New Jersey insanity defense without supporting expert testimony.
2. Whether excluding Arrington's proposed insanity defense absent expert testimony violated his constitutional right to present a complete defense.
3. Whether Arrington's proposed evidence, consisting essentially of his own testimony and the State's evidence concerning the crimes, was sufficient to warrant an insanity-defense jury instruction.

Disposition

affirmed