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PCAST Releases Report on Forensic Science in Criminal Courts

President’s Council of Advisors on Science and Technology recommends actions to strengthen forensic science and promote its more rigorous use in the courtroom.

Today, the President’s Council of Advisors on Science and Technology (PCAST) released its latest report to the President, Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods. “Forensic science” refers to the application of scientific or technical practices to the recognition, collection, analysis, and interpretation of evidence for criminal and civil law or regulatory issues. Developments over the past two decades—including wrongful convictions in which forensic science has played a role and scientific studies of forensic science methods—have called increasing attention to the question of the scientific validity and reliability of some important forms of forensic evidence and of testimony based upon them.

The study that led to the report was a response to the President’s question to his PCAST in 2015, as to whether there are additional steps on the scientific side, beyond those already taken by the Administration in the aftermath of a highly critical 2009 National Research Council report on the state of the forensic sciences, that could help ensure the validity of forensic evidence used in the Nation’s legal system.

PCAST concluded that two important gaps warranted the group’s attention: (1) the need for clarity about the scientific standards for the validity and reliability of forensic methods and (2) the need to evaluate specific forensic methods to determine whether they have been scientifically established to be valid and reliable. The study aimed to help close these gaps for a number of forensic “feature-comparison” methods—specifically, methods for comparing DNA samples, bitemarks, latent fingerprints, firearm marks, footwear, and hair.

In the course of its year-long study, PCAST compiled and reviewed a set of more than 2,000 papers from various sources, educated itself on factual matters relating to the interaction between science and the law, and obtained input from forensic scientists and practitioners, judges, prosecutors, defense attorneys, academic researchers, criminal-justice-reform advocates, and representatives of Federal agencies.

The report released today discusses the role of scientific validity within the legal system; explains the criteria by which the scientific validity of forensic methods can be judged; applies those criteria to the forensic feature-comparison methods mentioned above; and offers recommendations on Federal actions that could be taken to strengthen forensic science and promote its rigorous use in the courtroom.

The recommendations—which are directed at the National Institutes of Standards and Technology (NIST), the White House Office of Science and Technology Policy (OSTP), the Federal Bureau of Investigation (FBI) Laboratory, the Attorney General, and the judiciary—include the following:

  • NIST should perform evaluations, on an ongoing basis, of the scientific validity of current and newly developed forensic feature-matching technologies and should issue an annual public report on the results.
  • NIST should take a leadership role in transforming three important feature-comparison methods—DNA analysis of complex mixtures, latent-fingerprint analysis, and firearms analysis—from currently subjective methods, with their heavy reliance on human judgement, into objective methods, in which standardized, quantifiable processes require little or no judgment.
  • OSTP should coordinate the creation of a national forensic science research and development strategy.
  • The FBI Laboratory should undertake a vigorous research program to improve forensic science, building on its recent important work on latent-fingerprint analysis.
  • The Attorney General should direct attorneys appearing on behalf of the Department of Justice (DOJ) to ensure expert testimony in court about forensic feature-comparison methods meets the standards of scientific validity.
  • The Attorney General should revise and reissue for public comment the DOJ proposed “Uniform Language for Testimony and Reports” and supporting documents to bring them into alignment with standards for scientific validity.
  • When deciding the admissibility of expert testimony, Federal judges should take into account the appropriate scientific criteria for assessing scientific validity.

PCAST believes the findings and recommendations will be of use both to the judiciary and to those working to strengthen forensic science.


Eric Lander, William Press, S. James Gates, Jr., Susan L. Graham, J. Michael McQuade, and Daniel Schrag are members of the PCAST Forensic Science in Criminal Courts working group.

PCAST is an advisory group of the Nation’s leading scientists and engineers, appointed by the President to augment the science and technology advice availability to him from inside the White House and from cabinet departments and other Federal agencies. For more information about PCAST, please visit the PCAST website.