People v. Weinstein
591 N.Y.S.2d 715, 156 Misc. 2d 34, 1992 N.Y. Misc. LEXIS 537 (1992)
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Rule of Law:
In New York, when a defendant asserts an insanity defense, CPL § 60.55(1) creates an exception to the Frye standard, allowing a psychiatric expert to offer novel scientific evidence as an explanation for their diagnosis, provided it is a 'reasonably' clarifying basis. However, the stricter Frye 'general acceptance' standard still governs the admissibility of overarching scientific theories about the existence of a syndrome or the cause of human behavior.
Facts:
- Herbert Weinstein and his wife, Barbara, lived in a 12th-floor apartment in Manhattan.
- On January 7, 1991, Weinstein allegedly strangled his wife.
- Weinstein then allegedly threw her body from the apartment window to create the appearance of a suicide.
- Prior medical imaging had detected an arachnoid cyst within the protective coverings of Weinstein's brain.
- After being indicted, Weinstein underwent positron emission tomography (PET) scans, which revealed metabolic imbalances in his brain near the cyst.
- He also underwent skin conductance response (SCR) tests, which measured his autonomic nervous system's reactions to emotional stimuli.
- The SCR test results were consistent with those of individuals confirmed to have lesions in their brain's frontal lobes.
Procedural Posture:
- The State indicted Herbert Weinstein for murder in the second degree in a New York trial court.
- Weinstein's attorney filed notice of his intent to present an insanity defense, claiming Weinstein lacked criminal responsibility due to mental disease or defect.
- The defense intended to use PET scan and SCR test results as part of the basis for a psychiatrist's expert testimony.
- The District Attorney filed a pretrial motion to preclude the defense from introducing any testimony or evidence concerning the PET scans and SCR test results.
- The trial court held a pretrial evidentiary hearing on the District Attorney's motion.
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Issue:
Does New York's CPL § 60.55(1) permit a defendant asserting an insanity defense to introduce novel scientific evidence, such as PET scans and SCR test results, to explain the basis for a psychiatric diagnosis even if that evidence does not meet the 'general acceptance' standard of Frye v. United States?
Opinions:
Majority - Richard D. Carruthers, J.
Yes. CPL § 60.55(1) requires a court to permit a psychiatric expert in an insanity defense case to provide any explanation that reasonably serves to clarify their diagnosis, which creates a more lenient standard than the Frye 'general acceptance' test for evidence used for this purpose. The court reasoned that while New York typically adheres to the Frye standard for novel scientific evidence, the plain language of CPL § 60.55(1) carves out an exception specific to insanity cases. The statute's focus is on reasonableness, allowing an expert to explain the basis for their opinion, including reliance on diagnostic tests that may not yet be 'generally accepted' but are reasonably considered by professionals in forming a clinical diagnosis. However, the court distinguished this from overarching theories of causation (e.g., that a specific brain abnormality causes violence), which must still meet the higher Frye 'general acceptance' standard to be admissible. Therefore, the PET and SCR results are admissible as part of the reasonable basis for the psychiatrist's diagnosis of Weinstein, but not to prove a direct causal link between his brain abnormalities and violent behavior.
Analysis:
This decision establishes a significant, two-tiered framework for admitting scientific evidence in New York insanity defense cases, creating a crucial exception to the state's traditional adherence to the Frye standard. By allowing novel diagnostic evidence under a 'reasonableness' standard while retaining the stricter 'general acceptance' test for broader causal theories, the court balances a defendant's ability to present a full defense with the need to prevent 'junk science' from misleading a jury. This ruling opened the door for the use of emerging neuroscientific evidence in criminal trials to explain an expert's clinical opinion, setting a precedent that would influence how courts handle the intersection of law and rapidly evolving medical technology in assessing criminal responsibility.
