Fingerprint error rates and proficiency tests: What they are and why they matter

The reliability and probative value of a reported fingerprint match at trial is inextricably linked to the rate at which fingerprint examiners make errors. Therefore, it is important that jurors and other legal actors have valid information about the different types of errors, error rates, and scientific tests that can assist with error rate estimates. There is much confusion surrounding these issues and this paper addresses each using a question-and-answer style. Specifically, I describe the different types of errors (e.g., false positives, false negatives, and false alarms) and error rates, explain why they matter, and discuss how we might design proficiency tests to estimate key error rates. I also consider - and reject - a variety of skeptical arguments. For example, I reject the claim that information about the training and experience of an examiner provides sufficient information about risk of error. I reject the claim that industrywide error rates obtained from well-constructed proficiency tests are irrelevant to estimates of the risk of error in specific cases. I reject the claim that it is too difficult, expensive, or time consuming to implement a mandatory program of double-blind proficiency tests administered by disinterested parties.