Scientists call for more rigor in forensic science

A Perspectives article published in the Proceedings of the National Academy of Sciences calls for “more science in forensic science.”

PROVIDENCE, R.I. [Brown University] — Every day in American courtrooms, evidence from forensic science is used to help convince juries of defendants’ guilt or innocence. A group of scientists, including a Brown University physicist, is calling for more rigorous validation of the forensic tools used to administer justice in the U.S.

The group makes its case in a new Perspective article published today in the Proceedings of the National Academy of Sciences titled “A call for more science in forensic science.” Brown’s S. James Gates Jr. is a coauthor.

The article points out that many techniques used in forensic science — DNA analysis, analytical chemistry and death investigation as examples — were developed and rigorously validated by science well before their application in criminal justice. But other techniques like blood-stain pattern analysis and bite-mark analysis have been developed specifically for criminal justice applications. Many of these techniques lack proper scientific vetting, the authors argue, and some have been shown to be deeply flawed. Yet evidence from many of these is still admissible in court as a matter of precedent. 

The article calls for the broader scientific community to rally around colleagues in forensic science in advocating for research, testing and financial support. The authors also lament the termination of the National Commission on Forensic Science, a multi-stakeholder group within the U.S. Department of Justice that provided guidance on forensic issues.

Gates, who is a theoretical physicist, discussed the paper and his work in forensic science policy in an interview.


Q: How did you get involved in this issue?


While I was serving on the U.S. President's Council of Advisors on Science and Technology (PCAST) during the administration of President Obama, which was led by his science advisor, Dr. John Holdren, I was invited to become a commissioner on a body considering the development of policy for best practices in the forensic sciences. After meeting with principals at the U.S. Commerce Department, who had to convince me that as a theoretical physicist I could add value to this effort, I agreed.


Q: Forensic science is a long way from theoretical physics. What perspective do you bring to this?


All science rests on a universal foundation. The details of each discipline may be different, but the approach to extracting accurate evidence-based knowledge does not change. Most scientists would be shocked by the lack of: (a) systematics for quantifying errors, and (b) a foundational literature containing few observationally based publications, in forensic science.


Q: You argue in the paper that the responsibility for validating forensic techniques should lie outside the criminal justice setting. Could you explain a little more about that?


The answer is called “cognitive bias.” Let me give a simplified example. If I told you I was going to name two colors, and said the word “black,” it is almost impossible for you not to expect the next word would be “white.” This sort of subconscious anticipation or bias is almost unavoidable. Cognitive bias seems to be permitted in many current practices in the forensic science domain. 

Over centuries, most of science has developed in such a way to avoid this natural tendency. This is the main reason that science has been able to provide the most accurate measurements and predictions possible about nature.


Q: There was a body called the National Commission on Forensic Science — on which you served — that provided guidance on these issues, but it was terminated by the Justice Department last year. Could you describe what the commission did and why you think it was important?


The commission included federal, state and local forensic science service providers; research scientists and academics; law enforcement officials; prosecutors, defense attorneys and judges; and other stakeholders from across the country. The most important aspect of the NCFS was that it marked the first time all the members engaged in this important component of the criminal justice system met in a national forum to work toward common implementation of the use of science universally in their importance contributions to our society.

The commission’s complete output can be found online.

I would be remiss if I did not inform interested parties that the actual forensic scientists of this community are not simply abandoning these processes toward raising the quality of 'science' being used. There are many signs within this group that it has the capacity to meet this challenge. These have been most encouraging in the extreme for me.


Q: What do you see as the way forward in developing better standards for forensic science?


The criticisms I and other scientists have raised about the practices of forensic science are extremely limited to the techniques and practices used by forensics service providers and to courtroom testimony. We believe any area represented to the public as science must follow rules accepted with regard the primary role of accuracy in observation and measurement to which all other science are subject. 

As I have said before, if you are going to step into a courtroom and represent a technology or a set of procedures as being scientific, there should be an empirical basis for those statements, and presentations of forensic science in the courtroom should acknowledge that there is uncertainty in the result.

There have been some in the legal community, especially among prosecuting attorneys who have stated that to follow this rule for the definition of science is “one way” to do science. For those of us outside of forensic science, it is the only way — as has been stated by Dr. Eric Lander, McArthur Prize-winning geneticist and PCAST co-chair in recent article "Fixing Rule 702" in the Fordham Law Review.

I believe the larger scientific community must continue its engagement with the practitioners of forensic science to assure the public that its use in the criminal justice system convicts the guilty, but equally important exonerates the innocent.