Doubt Looms Over Forensic Science & the Criminal Justice System

The presumption of innocence—that a person is considered innocent unless proven guilty—is a legal right of an accused in a criminal trial. As such, the burden is always on the prosecution to collect and present evidence sufficient to convince a jury that the accused is guilty beyond a reasonable doubt.[1] Forensic evidence, in particular that backed by “real” science, has been used to ensure the accuracy of an accused being convicted and punished for a crime; and thus, the reliability of such evidence is paramount to the integrity of our criminal justice system. Raising doubts about the criminal justice system, a 2009 report by the National Academy of Science called into question forensic disciplines (DNA aside). According to this report, “Forensic science research is not well supported, and there is no unified strategy for developing a forensic science research plan across federal agencies. Relative to other areas of science, the forensic disciplines have extremely limited opportunities for research funding.” The 2009 report concluded that: “much forensic evidence—including, for example bite marks and firearm and tool mark identifications—is introduced in criminal trials without any meaningful scientific validation, determination of error rates, or reliability testing to explain the limits of the discipline.”

Shortly after the report, President Obama formed the Presidential Council of Advisors on Science and Technology (“PCAST”).[2]  In response to this and other studies and reports, in 2015, the President requested a review by PCAST of certain forensic disciplines, including the use of bite-mark, hair, footwear, firearm, and tool-mark analysis routinely used as evidence in trials across the nation.[3]

PCAST’s draft report, titled “Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods,” scrutinizes the use of forensic analysis in the criminal justice system. Though the final report is expected to be released sometime in the next few weeks, its findings are gloomy for forensic science supporters.  It concludes that much of the forensic analysis used in criminal trial is not scientifically valid—and might never be—and had not been independently and sufficiently scrutinized by “science based agencies” to have “foundational validity” in a way that it could meet the standard for whether evidence is based on reliable principles and methods.[4] While DNA and fingerprint[5] analysis meet this standard, severe doubts about the use of bite-mark, hair, footwear, firearm, and tool-mark analysis persist, despite their use in thousands of cases annually in both state and federal courts.[6]

The criminal justice community has chimed in on the PCAST report.  According to the president of the National Association of Criminal Defense Lawyer, Barry Pollack, the entire area of forensic science in criminal trials “cries out for further independent analysis.” He expects that criminal defense attorneys will use the final report to cross examine expert witnesses “hopefully to convince the judge that the jury should never hear from an expert who doesn’t have real science behind him. At a minimum it should allow the jury to decide what weight to give to any testimony.”[7] More pessimistically, the executive director of the fraternal Order of the Police, Jim Pasco, expressed criticism, stating “What they’ve done is turn the accepted reliability of expert witnesses and their evidence on their heads.…As a result there will be people who are not going to go to jail who should be incarcerated and some who are currently incarcerated will be released. The effect will be a threat to the public safety of American citizens.”[8]

Unsurprisingly, the final PCAST report will have some alarming effects as it will seriously draw into question, if not completely strike down, these age-old methods of convicting criminal defendants. It may create perhaps insurmountable challenges for prosecutors and cause old cases to be re-examined.[9] This presidentially-sought report is a step in the direction of protecting the constitutional guarantee to be presumed innocent and to a fair trial—but will it go too far?[10]



By Keobopha Keopong, Esq., Barnes Law

Keo Keopong is an associate attorney with Barnes Law, licensed to practice law in California.

The opinions expressed are those of the author and do not necessarily reflect the views of the firm, its clients, or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.

[1] Notably, this presumption of innocence is so important that countries worldwide also abide. It is considered an international human right under the United Nation’s Universal Declaration of Human Rights, article 11, which states "Everyone charged with a penal offence has the right to be presumed innocent until proved guilty according to law in a public trial at which he has had all the guarantees necessary for his defence." (

[2] “PCAST is an advisory group of the nation’s leading scientists and engineers who directly advise the President and the Executive Office of the President. PCAST makes policy recommendations in the many areas where understanding of science, technology, and innovation is key to strengthening our economy and forming policy that works for the American people.” (

[3] “The review is part of an ongoing, long-term investigation of decades of FBI microscopic hair analysis that the agency is conducting in partnership with the Department of Justice, the Innocence Project and the National Association of Criminal Defense Lawyers. the project launched in July 2013, and last year’s announcement covered the first 500 cases of an estimated 3,000 spanning from the 1970s up to 2000.” (


[5] “ ‘[T]he council said it would be appropriate to inform jurors that only two properly designed studies of the accuracy of fingerprint analysis have been conducted and they both found false positives ‘at detectable frequencies.’” (

[6] This report reviews some common forensic practices (aka feature-comparison disciplines, or pattern-matching practices) involving an “expert” examining evidence and determining whether it matches a particular image, person or object.” (



[9] “The FBI has begun to come to grasp with the ills of flawed forensic evidence. Last year the FBI admitted that, after reviewing 500 cases that employed microscopic hair analysis, examiner’s’ testimony contained erroneous statements in at least 90 percent of the cases.

Defendants in at least 32 of those cases received the death penalty, according to the FBI. Nine of those defendants have been executed, and five died of other causes while on death row. (

[10] The information contained in this post was drawn from the following sources:;;


** Updated news 09/21/2016: 

** Final PCAST Report: