In 1978, a cab driver was robbed and killed in front of his home. Police recovered a stocking mask near the scene of the crime and an FBI analyst testified that hairs found on the mask matched the hair of seventeen-year-old suspect Santae Tribble. He had half a dozen alibi witnesses, but the strength of this testimony and the prosecutor exaggerating that there was perhaps “one chance in ten million” that the hair could have belonged to anyone other than Tribble was enough for the jury to convict him of murder.
In 2012, DNA testing proved none of the hairs were Tribble’s, and one of the 13 hairs wasn’t even human but came from a dog. Sandra K. Levick, Tribble’s lawyer wrote, “Such is the true state of hair microscopy, two FBI-trained analysts could not even distinguish human hairs from canine hairs.”
This Is Not Unusual
Santae Tribble served three decades in prison and is one of the over 2,000 people that have been wrongfully convicted since 1989 according to The National Registry of Exonerations. This number grows every year and 2016 set another record with 166 exonerations. Many believe this is just the tip of the iceberg because in most cases there is no DNA or other new evidence available to prove innocence. Radley Balko, a journalist at the Washington Post who has covered this topic extensively, breaks this down, writing:
“The percentage of all cases in which DNA testing conclusively proves or disproves guilt is small — 10 percent at most. But the flaws in the system that DNA exposed in those 10 percent of cases almost certainly persist throughout the system, and likely at about the same rates. Today, provided that it’s done correctly (by no means a given, because human beings will always be doing the collecting), DNA testing can make us reasonably certain that the system will get it right nearly all the time for that 10 percent of cases. But if we don’t correct the problems DNA testing originally exposed in those 10 percent of cases, those problems will continue to plague the remaining 90 percent of cases.”
One problem that continues to plague the justice system is the use of unreliable forensic evidence. Out of the 351 cases in which the Innocence Project used DNA to exonerate wrongfully convicted defendants, flawed forensic evidence contributed in nearly half.
Many Americans, especially those who think shows like Forensic Files and CSI accurately represent real life, believe that forensic evidence presented in criminal trials must be valid. But we have known for years that many forensic evidence techniques are highly subjective and unreliable. This is especially true of the pattern-based methods like hair and bite-mark comparisons.
An NPR article outlines a particularly tragic example demonstrating this phenomenon:
“Levon Brooks and Kennedy Brewer are Mississippi men who spent a combined 30 years in prison for crimes they didn't commit. They were separately charged with sexually assaulting and murdering two 3-year-old girls — in two separate crimes — two years apart.
Dr. Steven Hayne, the pathologist who conducted both autopsies, said he suspected the girls had been bitten. A forensic dentist, Dr. Michael West, testified in both trials that the teeth marks found on both girls matched those of Brooks and Brewer.
After an investigation led by the Mississippi Innocence Project, Brooks and Brewer were exonerated by DNA evidence in 2008. The lab that cleared the men also generated a DNA profile of a new suspect — Justin Albert Johnson. He confessed to both crimes and is currently awaiting trial.”
It gets worse. The marks were likely not caused by human bites at all but from “routine decomposition or fish, turtle and insect activity in the water where the bodies were found,” according to an expert panel hired by the Innocence Project.
Bad Methods and Shoddy Science
Erroneous bite-mark evidence has contributed to over twenty wrongful convictions. There is no scientific evidence backing the validity of bite-mark analysis. And yet this kind of testimony is routinely deemed admissible in courtrooms across the country. In fact, not one court has ever rejected it.
Even with less subjective methods like fingerprint analysis, confirmation bias can lead to errors. In the 2004 Madrid train bombings, FBI examiners definitively declared that a fingerprint found on a bag containing explosives used in the attack matched a lawyer from Oregon named Brandon Mayfield. He was on a terrorism watch list and the FBI felt he was their best suspect. It later turned out the FBI examiners got it wrong. Spanish authorities matched the prints to an Algerian national named Ouhnane Daoud.
Mark Godsey writes about this case in his book Blind Injustice,
“Later, the FBI acknowledged that confirmation bias played a role in the misidentifications. Indeed, three different FBI fingerprint examiners — and Mayfield’s own defense expert — may have succumbed to the bias and erroneously declared a match as a result. This happened despite clear discrepancies between Mayfield’s print and the bomber’s, ones obvious to the Spanish experts. The biases of the American experts did not allow them to see those discrepancies. The experts saw only what they expected to see, and their minds did not register anything else.”
Despite countless examples and an extensive body of research demonstrating the extraordinary power of confirmation bias, most crime labs don’t actively safeguard against its influence. Godsey describes his experience as a federal prosecutor in New York City:
“In my days as a prosecutor, we routinely told experts examining our evidence what outcome we needed… It was run-of-the-mill for us. If it were a ballistics test, we might say, ‘Confirm that the bullets came from the defendant’s gun,’ or, ‘We believe these are from the defendant’s gun, so please run the test to confirm.’”
An expert in any other field conducting an experiment or analysis with this kind of blatant disregard for basic scientific standards would be denounced and their findings promptly dismissed.
If that’s not enough to undermine confidence in the work of crime labs, Godsey goes on to write,
“In some jurisdictions, it gets even worse — lab technicians are not only told the “right” answer before they begin, but they have a financial incentive to provide that answer to law enforcement. Indeed, some jurisdictions provide the lab with an additional fee — taken out of the defendant’s court costs! — which kicks in only if the defendant is convicted.”
Failure to Reform
Several scientific bodies have looked at this issue and found a lack of standards and routine use of unreliable forensic methods in criminal trials.
Countless stories and scientific reports have exposed the disastrous state of forensic science in American courtrooms. In 2009, the National Academy of Sciences (NAS) issued a scathing report titled, Strengthening Forensic Science in the United States: A Path Forward. This report outlined shortcomings in forensic techniques and made several recommendations for reform. Most significantly, it urged the creation of a National Institute of Forensic Science (NIFS) to “remove all public forensic laboratories and facilities from administrative control of law enforcement agencies and prosecutors’ offices.” And it advised that NIFS should “develop standard operating procedures… to minimize, to the greatest extent reasonably possible, potential bias and sources of human error in forensic practice.”
Sadly, eight years later, this advice has largely gone unheeded. And just last year, another report, this time from the President’s Council of Advisors on Science and Technology (PCAST), reiterated the shortcomings of forensic science and urged reforms. But then-Attorney General Loretta Lynch demurred, saying, “While we appreciate their contribution to the field of scientific inquiry, the department will not be adopting the recommendations related to the admissibility of forensic science evidence.”
In 2013, the Justice Department did adopt one recommendation from the NAS report, creating the National Commission on Forensic Science, but Jeff Sessions ended support for it and allowed its charter to expire this year, leaving much of its work unfinished.
No justice system is perfect, but countless stories and scientific reports have exposed the disastrous state of forensic science in American courtrooms. The least we can do is learn from these tragic cases and implement common-sense reforms to prevent more wrongful convictions based on junk science.