## Facts

- New York charged Herbert Weinstein with second-degree murder for the death of his wife.
- The People alleged Weinstein strangled his wife in their Manhattan apartment and then threw her body from a twelfth-floor window to make the death appear to be a suicide.
- Weinstein served notice that he would assert lack of criminal responsibility based on mental disease or defect.
- Weinstein planned to call a psychiatrist to testify that Weinstein was not criminally responsible because of mental disease or defect.
- The psychiatrist’s opinion relied on multiple sources, including interviews, physical and neuropsychological testing, and other information.
- The psychiatrist also relied on brain imaging using positron emission tomography (PET) and results from skin conductance response (SCR) testing.
- The PET scans revealed a cyst in Weinstein’s brain and metabolic imbalances in regions near the cyst.
- The SCR testing purported to show damage to the frontal lobes.
- The People moved to exclude evidence relating to the PET scans and SCR results.
- The court held an evidentiary hearing to determine admissibility of the PET and SCR evidence.

## Issues

1. Whether PET scan evidence offered in support of a lack-of-criminal-responsibility defense is admissible under New York’s Frye general-acceptance standard.
2. Whether SCR testing results are admissible under Frye, and, if not, whether a defense psychiatrist may still rely on and explain SCR results as part of the basis for an insanity opinion.
3. What limits should be imposed to prevent PET/SCR evidence from being presented as conclusive proof that a brain abnormality caused the charged criminal conduct.

## Decision

- The court denied the motion to exclude PET evidence and permitted testimony about PET scanning as a generally accepted method for measuring brain glucose metabolism, subject to proper foundation.
- The court found SCR testing had not achieved general acceptance as a diagnostic tool, but it did not impose a categorical bar on the defense psychiatrist referencing SCR results as part of the basis for the psychiatric opinion, with appropriate limits and foundation.
- The court restricted the use of PET and SCR evidence so it would not be presented as definitive, stand-alone proof of legal insanity or as a scientifically settled explanation that the brain findings caused homicidal behavior.

## Legal Principles

- Under Frye, scientific evidence based on a novel technique is admissible only if the relevant scientific community generally accepts the technique for the purpose for which it is offered.
- A court may distinguish between admitting a scientific technique as reliable for a limited medical measurement (e.g., metabolic activity shown on PET) and admitting broader behavioral inferences drawn from that measurement.
- Even when a technique is not generally accepted as a diagnostic tool (as with SCR here), a psychiatrist testifying on lack of criminal responsibility may be permitted to explain information relied upon in forming an opinion, so long as the testimony is properly grounded and the jury is not told the technique provides conclusive proof.
- Courts may limit neuroimaging and related testing evidence to avoid overstated claims that specific brain findings directly establish criminal irresponsibility or directly explain the defendant’s violent act.

## Conclusion

People v. Weinstein held that PET scan evidence, used to measure brain metabolism, satisfied Frye and could be admitted in support of a lack-of-criminal-responsibility defense, while SCR testing lacked general acceptance as a diagnostic method but could still be referenced in a limited way to explain the defense psychiatrist’s opinion, with safeguards preventing the evidence from being treated as definitive proof of legal insanity or direct causation of the homicide.


People v. Weinstein, 591 N.Y.S.2d 715, 156 Misc.2d 34 (1992)