Expert Testimony about Eyewitness Identification

This post addresses three recurrent issues concerning eyewitness identification: When, if at all, is expert testimony about eyewitness identification admissible? When, if at all, is an indigent defendant entitled to funds with which to hire an expert on eyewitness identification? May jury instructions, rather than expert testimony, be used to inform the jury about factors relevant to the accuracy of an eyewitness identification? When, if at all, is expert testimony about eyewitness identification admissible? Expert testimony must meet the standards set forth in Rule 702, meaning that it must be “based upon sufficient facts or data,” be “the product of reliable principles and methods,” and the witness must have “applied the principles and methods reliably to the facts of the case.” It must also be relevant, helpful to the jury, and not so unfairly prejudicial as to run afoul of Rule 403. Whether to admit expert testimony under these standards “is within the trial court’s discretion.” State v. McLean, 183 N.C. App. 429 (2007). See also Moore v. Hardee, 723 F.3d 488 (4th Cir. 2013) (summarizing, in a federal habeas case, that “expert testimony on eyewitness identifications is not automatically admitted; when allowed, its admissibility is generally at the court's discretion, both under federal and North Carolina law”); State v. Cotton, 99 N.C. App. 615 (1990) (the defendant in a sexual assault case sought to call a psychology professor to testify that “lighting, stress, cross-racial identification, priming of memory, unconscious transfer, and loss of memory over time [were] factors affecting the [...]