In February 2009, the National Research Council of the National Academies published a report that fundamentally changed how forensic science evidence is understood in the American legal system. Titled “Strengthening Forensic Science in the United States: A Path Forward,” the report was the product of a congressionally mandated study examining the state of forensic science disciplines used in criminal courts.
The findings were damning. After reviewing decades of research, practice, and validation data, the committee concluded that many of the forensic science disciplines routinely admitted in American courts lacked the scientific foundation necessary to support the conclusions drawn from them. It found that courts had been admitting testimony that overstated what the underlying science could actually demonstrate, that many forensic disciplines had no meaningful research base establishing their reliability, and that the adversarial legal system had failed to police these problems effectively.
The report is not ancient history. It remains the most comprehensive independent assessment of forensic science reliability ever conducted, its findings have been confirmed and extended by subsequent research, and its conclusions are directly relevant to criminal cases in Texas courts today.
What the Report Found
Lack of scientific validation. The committee found that many pattern-matching forensic disciplines (bite mark analysis, microscopic hair comparison, tool mark and firearms identification, footwear analysis) had never been subjected to the kind of rigorous empirical testing that would establish their accuracy, error rates, and reliability. “The simple reality,” the report stated, “is that the interpretation of forensic evidence is not always based on scientific studies to determine its validity.” Disciplines were being used in courts to convict defendants based on assumptions that had never been scientifically tested.
No standards for error rates. For most forensic disciplines, there were no established error rates (no systematic testing of how often examiners make mistakes, and no requirement that error rate information be disclosed to the jury). An examiner who testifies that a latent fingerprint “matches” a suspect to the exclusion of all other individuals is making a statistical claim that cannot be evaluated without knowing the false positive rate of the method. For most disciplines, that rate was unknown because no one had measured it.
Subjective methods presented as objective conclusions. Many forensic disciplines involve highly subjective judgments by trained examiners. The report found that subjectivity was rarely acknowledged in court testimony, where examiners frequently presented their conclusions with a degree of certainty that the underlying methodology did not support. An examiner who says a bite mark was “made by” a specific individual to “reasonable forensic certainty” is asserting a level of precision that the discipline had never demonstrated it could achieve.
Fragmentation and lack of oversight. The committee found that forensic science in the United States was fragmented across thousands of laboratories operating under widely varying standards, with no uniform accreditation requirements, no standardized training requirements, and no mechanisms for independent quality assurance. Laboratories attached to law enforcement agencies operated without the independence from prosecutorial pressure that scientific reliability requires.
The courtroom’s failure to police these problems. The report found that the legal system’s mechanisms for evaluating scientific evidence (the Daubert and Frye standards for admissibility, cross-examination, and adversarial testing) had largely failed to identify and exclude unreliable forensic science. Once a method was admitted in one jurisdiction, courts in other jurisdictions routinely admitted it without independent scrutiny. Precedent substituted for scientific validation.
The Specific Disciplines Criticized
The NAS report identified specific disciplines with significant reliability problems:
- Microscopic hair analysis. The report found that microscopic hair comparison (matching hairs from crime scenes to suspects by visual examination under a microscope) had never been validated as a reliable identification method. Subsequent FBI review of cases where hair analysis was used confirmed error rates that had resulted in wrongful convictions. Hair analysis is now generally considered unsuitable for identification testimony.
- Bite mark analysis. The committee found that the foundational premises of bite mark analysis (that human dentition is unique and that skin can reliably record dental impressions) had not been scientifically established. Bite mark analysis has been associated with numerous wrongful convictions.
- Firearms and tool mark identification. The committee found that the research base for firearms and tool mark identification was insufficient to support the categorical claims routinely made by examiners: that a bullet or cartridge case was fired from a specific weapon “to the exclusion of all other firearms.”
- Blood spatter analysis. The committee found that blood spatter interpretation lacked sufficient scientific study to support the precision with which conclusions were often presented.
What the NAS Report Did Not Criticize
The report distinguished these unreliable disciplines from well-validated forensic methods. DNA analysis of single-source samples was found to have a strong scientific foundation (the methodology has been empirically validated, error rates are measurable, and statistical interpretation frameworks are established). Toxicology and blood alcohol analysis using GC-MS, when properly performed and validated, were found to be scientifically sound, though the report noted that even reliable methods can produce unreliable results when not properly executed.
Why It Still Matters in Texas Courts
The NAS report does not bind Texas courts as a matter of law, but it remains the authoritative scientific assessment of forensic evidence reliability. In any case where the prosecution relies on pattern-matching forensic evidence (ex, bite marks, hair, tool marks, firearms, footwear) the NAS report’s findings are directly relevant to the admissibility and weight of that evidence. A defense attorney who can articulate those findings to a judge at a Daubert hearing, or to a jury during cross-examination of a forensic expert, is engaging the scientific validity of the prosecution’s evidence at the level it deserves.
If forensic science evidence is central to your case, contact Deandra Grant Law for a free, confidential consultation. Managing Partner Deandra Grant and Partner Douglas Huff both hold the ACS-CHAL Forensic Lawyer-Scientist designation. Deandra Grant also holds a Master’s Degree in Pharmaceutical Science and a Graduate Certificate in Forensic Toxicology. Call (214) 225-7117 or visit texasdwisite.com.