In adopting the present Criminal Code in 1978, our Legislature delineated the insanity defense to criminal charges as follows:
A person is not criminally responsible for conduct if at the time of such conduct he was laboring under such a defect of reason, from disease of the mind as not to know the nature and quality of the act he was doing, or if he did know it, that he did not know what he was doing was wrong.
[N.J.S.A. 2C:4-1 (emphasis added).]
As expressed in these terms, the insanity statute codifies the common-law "M'Naghten" test dating back to nineteenth-century English law. The Legislature has not revised this definition of insanity since Title 2C's enactment over fifty years ago.
The primary legal issue in this appeal is whether criminal defendants in New Jersey invoking N.J.S.A. 2C:4-1 are permitted to testify at trial about their own allegedly insane mental state without accompanying expert testimony from a qualified mental health professional. The court agrees with the trial judge that such lay testimony, untethered to admissible expert opinion substantiating the defendant's "disease of the mind," is inadmissible under our Rules of Evidence and insufficient to advance an insanity defense under N.J.S.A. 2C:4-1. This conclusion is supported by the history and text of the statute. It is also consistent with the case law of most states that have addressed the issue under the M'Naghten test.
Although policy arguments can be made and have been made to revise the criteria of N.J.S.A. 2C:4-1 and replace the traditional M'Naghten test with modern concepts of mental disorders, the Legislature has not done so. Nor has our Supreme Court invalidated the statute as unconstitutional or construed the law to allow lay testimony to suffice to establish a defendant's insanity. Consequently, this court holds that defendants must have expert opinion testimony to meet their burden of proving the defense of insanity. The court affirms the trial court's ruling that disallowed defendant in this case from testifying about his alleged insane state of mind without calling such an expert.
Judge Jacobs has filed an opinion concurring in the result in this case, but asserting that the law should permit defendants, in certain exceptional situations, to testify as lay witnesses in support of an insanity defense without corroboration by an expert witness.