What Happens to Accuracy When Photo Lineups Contain Non-Mated Rank-One Images From Large Galleries?

2026-07-23

AI Summary

This study investigates whether the size of a facial recognition gallery influences the risk of erroneous eyewitness identification when law enforcement selects the top-ranked non-matching image for lineup construction. Through a controlled experiment, the authors compare identification accuracy and confidence across gallery sizes of 500, 5,000, and 24,000 faces. The findings reveal, for the first time, a positive correlation between gallery size and both false identification rates and witness confidence in those errors. These results challenge prevailing forensic practices that directly incorporate algorithmic outputs into identification lineups and raise serious concerns about the reliability of using such identifications as sole justification for arrests.

Abstract

One-to-many facial identification is commonly used to match a probe image from surveillance video against a gallery of driver's licenses and/or booking photos. The algorithm's rank-one image from the gallery, or a human examiner's selection from the algorithm's top-ranked images, may then be placed in a photo lineup shown to a witness. Witness selection of the gallery image in the photo lineup may then lead directly to the person in the gallery image being arrested. This facial identification process is involved in at least 9 wrongful arrests. This work specifically examines whether the probability of a witness making an incorrect identification increases with the size of the gallery searched. We compare photo lineup accuracy when the "suspect" image is drawn from galleries of 500, 5,000, and 24,000 images. We find that larger galleries increase both the likelihood of a witness making an incorrect identification and their confidence in that (incorrect) identification. These results raise questions of whether an image resulting from such a facial identification process should be used in photo lineups and of whether results of a photo lineup alone should constitute probable cause for arrest.

Problem

• facial identification
• photo lineup
• gallery size
• witness identification
• wrongful arrest

Innovation

• facial identification
• photo lineup
• gallery size
• witness accuracy
• rank-one image