If “reliably” refers to the accuracy of a forensic examiner’s judgment in a given cases, the statement is true. Analysts of bitemarks, bullet striations, footwear marks, fingerprints, hair fibers, and complex DNA mixtures make correct positive and negative associations every day. That much is true of decisions based on the flip of a coin. It also could be true that every day these analysts also make incorrect judgments, incriminating the innocent and exonerating the guilty. Wouldn’t it be nice to know how many? And to know whether the correct statements are the result of demonstrable expertise?
I have great respect for judges, but most of the ones I know candidly admit that they lack the scientific training and knowledge to discriminate between scientifically valid, unvalidated, and invalid methods. The judges who admitted Dr. Louise Robbins’ breathtaking identifications based on the size and shape of feet (not friction skin ridge patterns) were “objectively neutral.” ( Robbins was an academic physical anthropologist also managed to identify a 3.5-million-year-old fossilized footprint in Tanzania as the mark of a prehistoric woman who was 5-and-one-half months pregnant.) Even today, the law in some jurisdictions does not require expert identification of things that jurors can see and compare for themselves (such as handwriting) to meet the standards established for scientific evidence generally.
The issue raised by PCAST is what it takes to show that forensic-science evidence is scientifically valid. An expert phrenologist would be subject to cross-examination and evaluation. That does not convert phrenology into a science.
District attorneys and defense counsel also present forensic-science testimony from experts who do not work in accredited laboratories, and, anyway, accreditation is not designed to examine the validity of the very premises of the field.
Someone sent me a copy of the draft, and I may as well quote from it on this point, since Eric Lander did in Thursday’s PCAST meeting:
The scientists' last sentence may not be entirely accurate. The report does more than merely “clarify the scientific standards.” It also applies them. It assesses the state of scientific knowledge in the fields it examined in light of those standards. But to do so is hardly “to usurp the Constitutional role of the Courts and decades of legal precedent and insert [themselves] as the final arbiter.” Anyone is free to disagree with the report’s definition of scientific validity and its assessments of the state of the science. Indeed, if time permits, I may advance some criticisms of my own.
But I will try to avoid empty rhetoric and undocumented claims that “PCAST ... ignored vast bodies of research, validation studies, and scientific literature authored by true subject matter experts” and eschewed “engagement with recognized subject matter experts.” To suggest that the PCAST draft report makes it necessary “to defend our constitutional adversarial system of criminal justice . . . against those who would seek to undermine the role of the courts, prosecutors, defense attorneys, and juries” is not merely unfounded—it is offensive.
More on the PCAST Report