Takeaway
In short, this case holds that CPL 60.55(1) permits reasonable diagnostic evidence supporting an insanity defense even when it falls short of Frye, but Frye still bars unaccepted scientific theories claiming that brain abnormalities cause violence.
Herbert Weinstein was indicted for second-degree murder for allegedly strangling his wife in their Manhattan apartment and then throwing her body from a twelfth-floor window to make the death appear to be a suicide. He gave notice that he would raise the affirmative defense of lack of criminal responsibility by reason of mental disease or defect.
After the indictment, Weinstein underwent PET brain scans and skin-conductance-response (SCR) testing. MRI and PET evidence showed an arachnoid cyst, displacement of part of the left frontal lobe, and metabolic abnormalities in the brain. Weinstein proposed to have a psychiatrist rely in part on the PET and SCR results in opining that organic brain damage impaired his cognitive capacity at the time of the alleged killing.
The District Attorney moved before trial to exclude all PET- and SCR-related evidence, arguing that the technologies lacked the general scientific acceptance required by Frye. Following an extensive evidentiary hearing with neurologists, psychiatrists, and nuclear-medicine experts, the court granted the motion only in part and set conditions governing the use of the evidence at trial.
Issue #1
Whether the Frye general-acceptance test governs every scientific item a psychiatric expert uses to explain a diagnosis in an insanity-defense case.
Holding
No. Under CPL 60.55(1), a psychiatric expert must be allowed to give any reasonable explanation that clarifies the expert's diagnosis, even if a particular diagnostic test has not independently achieved Frye general acceptance.
Reasoning
New York ordinarily applies Frye to novel scientific evidence. Frye protects against unreliable scientific claims by requiring that the underlying principle or technique be generally accepted in the relevant scientific field.
But CPL 60.55(1) specifically governs psychiatric testimony when criminal responsibility is at issue. Its command that an expert "must be permitted" to make any explanation reasonably serving to clarify the diagnosis gives psychiatric experts latitude to explain the clinical information on which their opinions rest.
That reading accords with the statute's Model Penal Code source and with the Court of Appeals' recognition that psychiatric testimony would be unduly weakened if an expert could not explain the basis of the diagnosis. Psychiatrists routinely consider a range of clinical information and tests, including information that may not itself satisfy Frye.
The statute does not abolish Frye altogether. Frye still governs broad scientific propositions, such as whether a mental disease or syndrome exists or whether a psychological or physiological theory validly explains human behavior. Those propositions are capable of controlled study and general acceptance; an individualized diagnostic judgment rests more heavily on clinical evaluation of the particular defendant.
Issue #2
Whether a psychiatric expert may rely on Weinstein's PET scans in forming and explaining an insanity diagnosis.
Holding
Yes. It is reasonable for the expert to consider PET evidence of the cyst and metabolic abnormalities, as well as the scan's quantitative results, in conjunction with the other diagnostic evidence.
Reasoning
The hearing established that fluorine-18 deoxyglucose PET scanning is generally accepted as a method of measuring regional glucose metabolism in the brain. Both defense and prosecution experts recognized PET's accepted role in depicting brain metabolic function.
Because PET is generally accepted for showing the cyst and regional metabolic abnormalities, it is plainly reasonable for a psychiatrist to consider those findings when assessing whether Weinstein had organic brain impairment affecting cognitive function.
The mathematical formulae used to quantify PET data had not themselves gained general acceptance. Still, PET specialists regularly used those formulae and relied on their results. Under CPL 60.55(1)'s less demanding reasonableness standard, a psychiatrist could consider the quantitative findings as one component of a broader diagnostic assessment.
Issue #3
Whether a psychiatric expert may rely on SCR testing as evidence of frontal-lobe dysfunction.
Holding
Yes, but only as corroborative information and subject to the applicable hearsay foundation requirement.
Reasoning
SCR testing was routinely used to assess autonomic nervous-system dysfunction, but it was not widely accepted as a direct diagnostic tool for frontal-lobe damage. The Iowa research nevertheless showed that SCR responses could distinguish persons with frontal-lobe abnormalities from normal subjects and from subjects with damage elsewhere in the brain.
The study was limited: it involved only 50 subjects, so SCR results could not reasonably be the sole basis for diagnosing frontal-lobe damage. But the research came from a respected neurologist, followed a careful protocol, and was peer reviewed before publication.
In those circumstances, it was reasonable for a psychiatrist to use SCR results as corroboration for the more definitive MRI and PET evidence showing abnormalities in Weinstein's frontal-lobe region.
Issue #4
Whether the PET and SCR findings may be relayed through a psychiatric expert without satisfying hearsay requirements.
Holding
Only partly. PET findings showing the cyst and metabolic imbalance may be related without further foundation, but quantitative PET results and SCR findings require testimony from a witness with direct knowledge.
Reasoning
Under People v. Stone and People v. Sugden, a psychiatric expert may rely on out-of-court material if professionals in the field accept that material as reliable in forming opinions. Alternatively, the expert may rely on material supplied by a witness who testifies at trial and is subject to full cross-examination.
The generally accepted PET imaging findings fall within the first Stone-Sugden exception. A psychiatrist may therefore testify to PET evidence of the cyst and metabolic imbalances without separate foundational testimony.
The quantitative PET formulae and the use of SCR testing to identify frontal-lobe damage lack the requisite general acceptance. Those results may be included in the psychiatrist's explanation only if a witness with direct knowledge supplies the necessary foundation and is available for cross-examination.
Issue #5
Whether the defense may present theories that arachnoid cysts or frontal-lobe hypometabolism directly cause violence, or that the somatic-marker theory explains Weinstein's conduct.
Holding
No. These causal and behavioral theories had not achieved general acceptance in psychiatry, psychology, or neurology.
Reasoning
Although the evidence supported the accepted proposition that frontal-lobe damage may impair reasoning, judgment, insight, and foresight, it did not support a generally accepted proposition that an arachnoid cyst directly causes violent behavior. Even the defense expert did not establish scientific research supporting that causal claim.
The proposed theory that reduced frontal-lobe glucose metabolism causes violence was also premature. The principal research involved only four patients, each of whom had other serious conditions that could explain the behavior, and its authors treated the findings as preliminary rather than conclusive.
The somatic-marker theory likewise had not gained general acceptance as an explanation for aberrant behavior. At most, it was a possible explanation offered in preliminary research for autonomic-response findings; it could not be introduced as an established scientific account of Weinstein's conduct.