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Why Criminal Law Ignores Science

Better investigative techniques are not being implemented despite the fact that simple changes would reduce wrongful convictions

by Josh D. Lee
February 18, 2013 | A version of this story appeared in Volume 91, Issue 7

Credit: New York University Press
FAILED EVIDENCE: Why Law Enforcement Resists Science, by David A. Harris, New York University Press, 2012, 269 pages, $35 hardcover (ISBN: 978-0814790550)
Title of book and author, with photo of actual fingerprints—three from right hand and three from left.
Credit: New York University Press
FAILED EVIDENCE: Why Law Enforcement Resists Science, by David A. Harris, New York University Press, 2012, 269 pages, $35 hardcover (ISBN: 978-0814790550)

According to statistics kept by the Innocence Project ( there have been more than 300 postconviction DNA exonerations in the U.S. Those people exonerated had been convicted of horrible crimes they did not commit. Most have spent many years in prison, 13 years on average, and many have lost everything. Eighteen of these people were sentenced to die for crimes they did not commit. Some say these data prove that our system is working. This could not be further from the truth.

Wrongful convictions do four kinds of harm. First, they obviously do great harm to the innocent individual who is convicted of a crime. Second, the victim of the crime has to go without closure of the real perpetrator being caught and punished. Third, the real rapist or murderer is allowed to go free and commit more crimes, harming more people. Last, society’s confidence in the U.S. criminal justice system is diminished when we find out an innocent person was convicted.

The system desperately needs changes, and it needs them fast. In his book, “Failed Evidence: Why Law Enforcement Resists Science,” David A. Harris, a law professor at the University of Pittsburgh, discusses the three most common causes of wrongful convictions, makes recommendations to help right the ship immediately as well as long term, and takes on law enforcement and prosecution that refuse to implement any meaningful changes—even in the face of scientific proof that doing so would decrease the number of wrongful convictions.

This “resistance to sound, science-based police investigative methods” is the theme of “Failed Evidence.” The book is an easy and informative read best suited for policymakers, scientists, advocates, judges, prosecutors, law enforcement, defense attorneys, and anyone with a general interest in the American criminal justice system. Truth be told, anyone who might find themselves sitting in the chair of a juror should read Harris’ book before sitting in judgment of a fellow human.

Early in “Failed Evidence,” Harris uses the case of Brandon Mayfield to summarize the general problem with police investigation techniques, the denial of a problem, and the resistance to any meaningful change.

In 2004, bombs exploded in commuter trains in Spain, killing 191 people and injuring approximately 1,800 more. Spanish authorities found a partial fingerprint on a piece of evidence from one of the crime scenes. They sent a copy of this print to the FBI where a senior fingerprint examiner made “a 100% identification” that the print belonged to a Brandon Mayfield. Three other fingerprint “experts” also examined the print, and all confirmed that it indeed was Mayfield’s fingerprint.

The interesting part is that Mayfield was an attorney from Oregon. As a result of this “match” the FBI arrested Mayfield and incarcerated him for two weeks. All of this despite the fact that he did not even have the valid passport that he would have needed to travel to Spain.

When shown this “match,” the Spanish police were very doubtful and offered to have the FBI come to Spain and examine the original print. Convinced that their experts had made a correct identification, the FBI refused the Spanish authorities’ offer. After Spanish authorities matched the print to an Algerian man living in Spain, the FBI finally decided to admit its mistake. It issued an apology to Mayfield and settled a lawsuit with him out of court.

Harris details glaring problems in the FBI’s methodology that came to light because of the Mayfield case. One was that the verification by the three confirming examiners “ignored one of the most basic principles of scientific testing: The verification was not a ‘blind’ test.”

Harris then examines the changes implemented by the FBI in response to this fiasco and finds the changes to be drastically lacking. He says the response was one of “resistance and denial: resistance to change and denial of the existence of a problem.” More than six years after the FBI’s misidentification, one that could have easily sent an innocent man to prison for the rest of his life, the fingerprint division still does not use blind confirmation testing in every case. Not only does the FBI resist change, it also denies that there is a problem. One of the confirming examiners later told the Chicago Tribune, “I’ll preach fingerprints until the day I die. They’re infallible.” This sets up the theme that reverberates throughout the rest of the book.

This, then, is the problem as Harris describes it: “With the exception of DNA (and then, only sometimes), most of our police and prosecutorial agencies do not welcome the findings of science; they do not rush to incorporate the latest scientific advances into their work. On the contrary, most … resist what science has to say about how police investigate crimes. The best, most rigorous scientific findings do not form the foundation for the way most police departments collect evidence, the way they test it, or the way they draw conclusions from it. Similarly, most prosecutors have not insisted upon evidence collected by methods that comply with the latest scientific findings in order to assure that they have the most accurate evidence to use in court.”

As a starting point for the discussion, Harris looks at what science really is and questions whether forensic science even qualifies as a science at all. At the root of science lies the scientific method. Following its principles allows us to infer certain knowledge from the unknown. It gives us confidence that our conclusions are correct and built upon a strong foundation and not merely based upon beliefs or hunches. Without the adherence to scientific principles the study or effort is lacking rigor and is not a “scientific” venture.

Scientific fields such as DNA analysis have been thoroughly tested. By contrast, Harris observes, many forensic science disciplines were creations of the criminal justice or law enforcement system and are not born of the scientific method. As a result, “many of the common forensic science disciplines have never been exposed to stringent scientific inquiry to gauge their accuracy, limitations, and foundations.” They don’t, in fact, qualify as science and are given too much credibility by the law and the courts.

Harris then dives into identifying the problems with the three most common causes of wrongful convictions. DNA exonerations over the past 24 years “prove that traditional techniques of eyewitness identification, suspect interrogation, and forensic testing contain fundamental flaws that have resulted in miscarriages of justice,” he writes. Harris discusses the science involved with improving each of these areas and their respective disciplines.

◾ Eyewitness Identification Mistaken eyewitness identifications are the greatest cause of wrongful convictions in the U.S. Almost 75% of DNA exoneration cases involved incorrect eyewitness identification. Decades of social science research show that eyewitness identification is not nearly as strong evidence as most people believe. Harris gives recommendations to make identification more reliable and less likely to elicit incorrect eyewitness identifications, as well as the research that supports his recommendations.

◾ Police Interrogation Techniques False confessions come into play in 25% of wrongful convictions. A confession is likely the strongest form of evidence a judge or jury can hear. When a person confesses, it removes all doubts about their guilt or innocence, and the more serious the crime the more difficult it is for observers to believe someone would confess to a crime they did not commit. Through exonerations, DNA evidence has proven that people in fact sometimes do confess to crimes they are not guilty of, even without the involvement of physical abuse, intoxication, or mental health issues. Harris makes recommendations for changing police interrogation techniques aimed at reducing the number of false confessions while at the same time not decreasing the number of actual true confessions.

◾ Forensic Science According to recent statistics by the Innocence Project, forensic science played a role in 51% of wrongful convictions. Harris discusses some of the common problematic disciplines, including fingerprint identification, firearms identification, impression and pattern evidence, analysis of hair and fiber, forensic odontology, and blood pattern analysis. The bottom line is that some of these disciplines must be banned from the courtroom until they have been rigorously tested using the procedures of legitimate science, and others must have their procedures altered to include scientific best practices.

Harris devotes two chapters to a discussion of possible reasons for the resistance put forth by too many law enforcement and prosecutorial agencies. He makes it clear that he believes good men and women go into jobs as police officers and prosecutors to do good and make a positive impact on society. If that is in fact the case, then why do so many resist changes that would make the system better and result in fewer wrongful convictions? Harris discusses various obstacles to change that are present in all of us and proposes that there are institutional barriers with the way our system operates that also add to the problem.

The final few chapters lay out 16 specific recommendations that must be implemented to help make our system the best it can be and praise those leaders in law enforcement and prosecution who have taken brave steps to make positive changes. Their actions were made in the face of institutional and political pressures against making any changes. Harris also calls on defense lawyers to challenge procedures that are lacking. He maintains that judges must be willing to enforce legal limitations on admissible evidence in criminal cases just as is done in civil cases.

Harris paints a picture suggesting that together we can make a difference. We will never be perfect, but we can do things much better. “Ignoring science, when doing so increases the risk of wrongful convictions, simply does not square with justice or fairness,” he writes. Positive change must happen and as Harris concludes, “Justice demands no less.”

Graphic presents data on 300 convictions overturned on the basis of DNA evidence with headline: 300 Exonerations and Counting.
Credit: Innocence Project
Graphic presents data on 300 convictions overturned on the basis of DNA evidence.

Josh D. Lee is a criminal defense attorney based in Vinita, Okla., who specializes in defending people accused of driving under the influence. He is also a member of the American Chemical Society and serves as the forensic science cochair for the ACS Division of Chemistry & the Law.


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