## Facts

- A federal grand jury indicted Edward M. Mezvinsky on 66 counts alleging fraud and related financial crimes committed from 1989 through December 2001; a superseding indictment added three additional counts based on conduct while on pretrial release.
- The charges included mail fraud (18 U.S.C. § 1341), wire fraud (18 U.S.C. § 1343), bank fraud (18 U.S.C. § 1344), false statements (18 U.S.C. §§ 1001, 1014), false tax returns (26 U.S.C. § 7206(1)), and currency structuring (31 U.S.C. § 5324(a)(3)).
- Mezvinsky filed notice under Fed. R. Crim. P. 12.2 that he intended to present a mental-condition defense.
- After later withdrawing any affirmative insanity defense under 18 U.S.C. § 17, Mezvinsky proceeded under Rule 12.2(b), seeking to introduce expert testimony to negate the specific intent elements of the fraud offenses.
- The defense relied primarily on a 2001 PET scan allegedly showing frontal-lobe abnormalities, with experts proposing that such abnormalities were consistent with impaired frontal-lobe functioning affecting his ability to form specific intent.
- Defense experts conceded limits, including (i) no established scientific link between the PET findings and a psychiatric condition mapping to the mens rea elements of the charged crimes, and (ii) inability to infer, from a single 2001 scan, Mezvinsky’s brain function during the prior twelve-year charged period.
- The government moved pretrial to exclude or restrict the proposed mental-condition evidence as unreliable, lacking relevance to mens rea, confusing to the jury, and inconsistent with the Insanity Defense Reform Act (IDRA).

## Issues

1. Whether Rule 12.2(b) permits expert mental-condition testimony based largely on a PET scan to negate the specific intent required for federal fraud offenses when the testimony lacks a reliable scientific basis and a reliable temporal connection to the charged conduct.
2. Whether the IDRA limits mental-disease evidence offered to negate mens rea when the defendant disclaims an insanity defense but presents a diminished-capacity-style theory.
3. Whether the proposed expert testimony satisfies Fed. R. Evid. 702 (reliability and fit) and should be excluded under Fed. R. Evid. 403 due to risk of confusing or misleading the jury.

## Decision

- The court granted the government’s motion in substantial part, substantially limiting Mezvinsky’s proposed mental-condition defense.
- The court held that Mezvinsky could not present an insanity-like theory indirectly after withdrawing an insanity defense governed by 18 U.S.C. § 17.
- Applying Fed. R. Evid. 702 and Daubert, the court excluded the PET-scan-based expert testimony to the extent it purported to show Mezvinsky lacked the mens rea required for the charged offenses.
- The court concluded the proffered opinions lacked a reliable scientific foundation tying PET findings to specific-intent elements and lacked a reliable basis to relate a 2001 scan to Mezvinsky’s mental state throughout the charged years.
- The court also found the evidence posed a substantial risk of confusing or misleading the jury, supporting exclusion or restriction under Rule 403.

## Legal Principles

- Under the IDRA (18 U.S.C. § 17), insanity is a limited affirmative defense requiring proof that, due to a severe mental disease or defect, the defendant was unable to appreciate the nature and quality or wrongfulness of his acts; it cannot be repackaged as a broad diminished-responsibility theory.
- Rule 12.2(b) may allow mental-condition evidence only insofar as it directly negates a required mental element; it does not authorize generalized explanations of criminal conduct based on impaired judgment or impulse control.
- Expert testimony offered to negate mens rea must satisfy Rule 702 and Daubert by demonstrating reliable methodology and a valid fit between the expert’s conclusions and the specific legal elements in dispute.
- Even potentially relevant scientific evidence may be excluded under Rule 403 if its probative value is substantially outweighed by the danger of confusing or misleading the jury, particularly where complex neuroimaging evidence may be overstated.

## Conclusion

The court largely barred Mezvinsky’s PET-scan-based mental-condition evidence because it did not reliably connect neuroimaging findings to the specific-intent elements of the charged fraud offenses during the charged period and because permitting the proffer risked circumventing the IDRA’s limits on mental-disease defenses.


United States v. Mezvinsky, 206 F. Supp. 2d 661 (E.D. Pa. 2002)