United States v. Llera Plaza

Carlos Llera Plaza (defendant) was on trial for drug and murder charges. The government (plaintiff) sought to introduce expert testimony from Federal Bureau of Investigation (FBI) fingerprint examiners. In order to identify fingerprints found at the crime scene, the FBI examiners used the ACE-V procedure. The ACE-V procedure allowed an examiner to compare a fingerprint from an unknown person (a latent print) with a fingerprint from a known person (a rolled print). Specifically, the examiner determined whether the latent print and the rolled print shared characteristics. Based on the number of shared characteristics, the examiner expressed an opinion as to whether there was a match between the latent print and the rolled print. Llera Plaza filed a motion to exclude testimony from the FBI examiners. The district court found that no persuasive information existed regarding the ACE-V procedure’s rate of error. Consequently, the district court ruled that the FBI examiners were not permitted to express an opinion as to whether there was a match between a latent print and a rolled print. The government filed a motion for reconsideration, arguing that the district court should reverse its ruling. The district court held an evidentiary hearing so that new evidence could be submitted. New evidence was submitted indicating that the FBI assessed the ability of its examiners to use the ACE-V procedure. Indeed, the FBI designed proficiency assessments that required examiners to match a latent print with a rolled print. The examiners made very few mistakes on these assessments, such that the rate of error was just under 1 percent. After the evidentiary hearing was concluded, the district court took the motion for reconsideration under advisement.