## Facts

- Jason Gill was shot and killed outside his Chicago home at about 11:20 p.m. on May 3, 2008.
- The prosecution’s proof of identity rested primarily on one eyewitness, Lydia Clark, a friend of Gill’s sister who frequently visited the home.
- Clark testified she had previously seen the shooter—known to her only as “Lucky”—multiple times on a porch across the street but had never spoken to him.
- Clark said she and Gill were on Gill’s front porch when a man approached wearing a hoodie (hood down) and holding a black gun.
- Observation conditions were challenged: it was dark, streetlights were on, and the porch light was off.
- Clark later identified Eduardo Lerma as the shooter; the defense challenged the reliability of that identification and pointed to the absence of substantial corroborating evidence tying Lerma to the shooting.
- Before trial, Lerma sought to introduce expert testimony describing scientifically recognized factors that can reduce eyewitness-identification accuracy; the trial court excluded the testimony as within ordinary juror knowledge.
- A jury convicted Lerma of first-degree murder (with a firearm enhancement) and aggravated discharge of a firearm; he appealed.

## Issues

1. Whether the trial court abused its discretion by excluding defense expert testimony on the reliability and limitations of eyewitness identification where the State’s case depended largely on a single eyewitness.

## Decision

- The appellate court held the trial court abused its discretion by categorically excluding expert testimony on eyewitness identification.
- The court reversed Lerma’s convictions and remanded for a new trial.
- The court concluded the exclusion was not harmless because the identification evidence was central and contested and the jury lacked specialized explanatory evidence relevant to evaluating it.

## Legal Principles

- Expert testimony is admissible when it will assist the trier of fact on matters beyond ordinary juror knowledge; admissibility requires a case-specific assessment, not categorical exclusion.
- Eyewitness-identification reliability involves scientifically studied phenomena that may be counterintuitive to lay jurors, including limited correlation between witness confidence and accuracy and effects of stress, lighting, weapon focus, cross-racial identification, and identification procedures.
- Cross-examination and general credibility instructions may be insufficient substitutes for expert explanation of specialized research bearing on perception and memory.
- When identity is the central disputed issue and the prosecution’s case substantially depends on a single eyewitness identification, excluding otherwise reliable and relevant expert testimony can be an abuse of discretion requiring a new trial.

## Conclusion

Because the prosecution’s case rose or fell on a single eyewitness identification made under contested viewing conditions, the trial court’s refusal to allow a properly proffered eyewitness-identification expert deprived the jury of relevant specialized assistance, warranting reversal and remand for a new trial.


People v. Lerma, 19 N.E.3d 95 (Ill. App. Ct. 2014)