## Facts

- A 13-year-old complainant was robbed at knifepoint on subway stairs in Manhattan; the encounter lasted only seconds.
- The assailant approached her for change, then stepped in front of her, held a knife near her throat, demanded her gold chain, ripped it off, and fled.
- The complainant gave police a description of the robber; she was the only eyewitness.
- The prosecution presented no corroborating physical evidence or other eyewitness testimony linking the defendant to the robbery; the case depended on the complainant’s later identification.
- At trial, after the prosecution rested, the defense sought to call an expert on factors affecting eyewitness reliability (including stress, violence, weapon focus, exposure time, cross-racial identification, and the confidence/accuracy relationship).
- The trial court denied the request outright without conducting a Frye hearing; the defendant was convicted of first-degree robbery.
- The Appellate Division affirmed; the defendant appealed.

## Issues

1. Whether the trial court abused its discretion by categorically excluding expert testimony on eyewitness-identification reliability without first conducting a Frye hearing.
2. Whether, in a case turning on a single eyewitness identification with little or no corroborating evidence, exclusion of otherwise relevant, scientifically grounded expert testimony requires reversal and a new trial.

## Decision

- The New York Court of Appeals reversed the conviction and ordered a new trial.
- The court held the trial judge abused discretion by denying the defense request for an eyewitness-identification expert without holding a Frye hearing.
- The court treated the case as one in which the proof “turned” on an uncorroborated identification and the proposed testimony addressed factors that could assist the jury.

## Legal Principles

- When a prosecution case turns on eyewitness identification with little or no corroborating evidence, a trial court may abuse its discretion by excluding relevant expert testimony on eyewitness reliability that rests on generally accepted scientific principles.
- A categorical denial of such testimony without a Frye inquiry is improper where the defense proffers recognized scientific topics bearing on reliability (e.g., stress, weapon focus, brief exposure, cross-racial identification, and the limited value of witness confidence).
- Frye’s “general acceptance” standard governs the admissibility of expert testimony grounded in scientific research on memory and perception.

## Conclusion

The Court of Appeals required a new trial because the prosecution’s proof rested on a single, uncorroborated eyewitness identification and the trial court excluded proffered expert testimony on eyewitness reliability without conducting a Frye hearing to assess the scientific basis for the testimony.


People v. Abney, 13 N.Y.3d 251, 918 N.E.2d 486 (N.Y. 2009)