The National District Attorneys Association’s Slam: PCAST "Usurps the Constitutional Role of the Courts"

A few days ago, the National District Attorneys Association issued a press release entitled “National District Attorneys Association slams President’s Council of Advisors on Science and Technology report.” That these attorneys have a negative reaction to criticism of their witnesses is not surprising, but what are their arguments? Is the slam a devastating critique, bombastic oratory, or something in between? Here are the principal arguments and some thoughts on them:

The forensic science disciplines that the PCAST authors attack are (and have been) reliably used every day by investigators, prosecutors, and defense attorneys across the United States to aid in both exonerating the innocent and convicting the guilty.

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]n each instance that such evidence is used, the process of presenting and cross examining the forensic evidence is overseen by objectively neutral judges whose role is to fairly supervise the introduction of evidence into trials and to act as “gatekeepers” to determine the reliability and admissibility of forensic evidence on a case-by-case basis.

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.

As with all evidence presented in criminal courts, this forensic scientific evidence is subject to cross-examination as well as evaluation by the Court.

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.

Many accrediting bodies consisting of world-renowned scientists and highly skilled experts evaluate forensic labs and practitioners, helping to guarantee that only qualified forensic experts testify to solid forensic facts in our courts.

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.

PCAST has taken it upon itself to usurp the Constitutional role of the Courts and decades of legal precedent and insert itself as the final arbiter of the reliability and admissibility of the information generated through these forensic science disciplines.

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:

Judges’ decisions about the admissibility of scientific evidence rest solely on legal standards; they are exclusively the province of the courts. But, the overarching subject of the judges’ inquiry is scientific validity.⁶ It is the proper province [of] the scientific community to provide guidance concerning scientific standards for scientific validity.⁷

7. In this report, PCAST addresses solely the scientific standards for scientific validity and reliability. We do not offer opinions concerning legal standards.

(1) The admissibility of expert testimony depends on a threshold test of, among other things, whether it meets certain legal standards embodied in Rule 702. These decisions about admissibility are exclusively the province of the courts.

(2) Yet, as noted above, the overarching subject of the judge’s inquiry under Rule 702 is “scientific validity.” It is the proper province of the scientific community to provide guidance concerning scientific standards for scientific validity.

PCAST does not opine here on the legal standards, but seeks only to clarify the scientific standards that underlie them.

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.

Index to comments and cases on the PCAST report