Publication Date

Winter 2021


In New York, an illogical and arbitrary common-law rule of evidence, the corroboration rule, governs the admissibility of expert testimony on the reliability of eyewitness identification. On one hand, the New York Court of Appeals has correctly held that expert testimony regarding the factors that undermine an identification’s reliability (the identification’s cross-racial nature, for example) can provide “valuable” assistance to a jury. But on the other hand, the Court has repeatedly held that a trial court can bar that expert testimony if it determines that the eyewitness identification is corroborated by accurate evidence. This is so, the theory goes, because corroboration renders expert-identification testimony less “important” and renders it “reasonable” for a judge to conclude that the identification was accurate.

This Article challenges the flawed corroboration rule, arguing that the Court of Appeals should abandon its corroboration approach and instead hold that the apparent strength of the prosecution’s case is irrelevant to the admissibility of expert testimony challenging that case. The corroboration rule impairs the fact-finding process, violating the fundamental rule that jurors, not courts, assess the reliability and weight of the evidence. Under the corroboration approach, courts usurp the jury’s power to resolve classic questions of fact: the identification’s reliability, the weight of the expert’s testimony, and the strength of the so-called corroboration. In every other area of our law, these classic factual questions are reserved for the jury. The corroboration rule is an anomaly.

The anomalous corroboration rule creates serious doctrinal inconsistencies. No other class of experts—and certainly no prosecution experts—are barred because the adversary’s case seems strong. The corroboration rule also leads to arbitrary and unpredictable results, requiring courts to determine whether the purported corroboration seems reliable enough to bar expert-identification testimony. As a result, appellate decisions in this arena often look like summation battles, with judges debating, in fine detail, the corroboration’s reliability. That battle should be reserved for the jury.

Common law aside, the corroboration rule violates the constitutional right to present a complete defense under Holmes v. South Carolina, 547 U.S. 319 (2006), and the Sixth Amendment’s guarantee of the right to call witnesses in one’s “favor.” Like the common law, the Constitution prohibits courts from blocking material defense evidence because a judge finds the government’s evidence reliable or strong.

The Court of Appeals should abandon the corroboration rule and instead hold that the testimony of a qualified expert on eyewitness identifications is admissible if it satisfies the traditional standards governing all other classes of expert testimony: (1) it is relevant; (2) its subject matter is beyond a jury’s common knowledge; and (3) it is generally accepted as reliable. The existence of corroborative evidence is irrelevant to the admissibility analysis.


He would like to thank the CUNY Law Review staff for their assistance in editing and preparing this article. Their work was invaluable. Matthew would also like to thank those who took the time to review the article, including his wife Anthe Bova, his brother Justin Bova, and his many public-defender colleagues.

Included in

Law Commons



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.