The Coming Paradigm Shift in Forensic Identification Science Michael J. Saks1 and Jonathan J. Koehler2 Converging legal and scientific forces are pushing the traditional forensic identification sciences toward fundamental change. The assumption of discernible uniqueness that resides at the core of these fields is weakened by evidence of errors in proficiency testing and in actual cases. Changes in the law pertaining to the admissibility of expert evidence in court, together with the emergence of DNA typing as a model for a scientifically defensible approach to questions of shared identity, are driving the older forensic sciences toward a new scientific paradigm. Little more than a decade ago, forensic individualization scientists compared pairs of marks (handwriting, fingerprints, tool marks, hair, tire marks, bite marks, etc.), intuited whether the marks matched, and testified in court that whoever or whatever made one made the other. Courts almost never excluded the testimony. Cross-examination rarely questioned the foundations of the asserted expertise or the basis of the analyst_s certainty. Today, that once-complacent corner of the law and science interface has begun to unravel—or at least to regroup. The news carries reports of erroneous forensic identifications of hair, bullets, handwriting, footprints, bite marks, and even venerated fingerprints. Scientists have begun to question the core assumptions of numerous forensic sciences (1–6). Federal funding has materialized to support research that examines long-asserted but unproven claims. Courts have started taking challenges to asserted forensic science expertise seriously (1). A dispassionate scientist or judge reviewing the current state of the traditional forensic sciences would likely regard their claims as plausible, underresearched, and oversold. The traditional forensic individualization sciences rest on a central assumption: that two indistinguishable marks must have been produced by a single object….