More than 150 men and women in American prisons were exonerated in 2018, according to a recent report by a registry that tracks wrongful convictions. Combined, these individuals spent more than 1,600 years in prison, a record for the database, which has data back to 1989. The leading culprit in convicting innocent people was official misconduct, according to the report by the National Registry of Exonerations. Nearly one third of these cases involved a police corruption scheme in Chicago through which a police officer framed individuals on drug charges. Another prominent factor in wrongful convictions across the country was misleading forensic evidence. A close look at these cases reveals how experts in fields like hair analysis, bite marks and DNA analysis have used exaggerated statistical claims to bolster unscientific assertions. Once experts meet the qualifications to take the stand in a courtroom, there are few limits on the words that come out of their mouths. “An expert can say whatever they want,” said Simon Cole, the director of the registry and a professor of Criminology, Law and Society at UC -Irvine. That includes offering up invented odds like “one in a million” or “1 in 129,600,” the registry says. “A lot of the problem with forensic testimony is that the diagnosticity is overstated,” said Barbara O’Brien, a professor at the Michigan State University College of Law and author of the report. A hair sample at the crime scene that resembles a suspect’s hair “gets dressed up with this scientific certainty that isn’t justified,” she said. Here are three examples from the study’s case files. In 2013, the F.B.I. reported that testimony asserting that microscopic hair comparison could produce a “match” between two hairs was scientifically invalid. Four years later, a man named Glenn Payne was still grappling with the consequences of three sets of misleading odds. In 1990, when he was 28, he was charged with sexually abusing his 2-year-old neighbor. Upon arrest, Mr. Payne was asked to disrobe. A hair was left behind on a sheet of butcher paper. Investigators located a second hair on a tablecloth draped over the girl. In court, a lab analyst testified that the hair on the butcher paper had a 1 in 2,700 chance of matching someone other than the victim, and the hair on the tablecloth had a 1 in 48 chance of belonging to someone other than Mr. Payne. He then multiplied these figures together to get a “1 in 129,600” chance of anything other than a random occurrence. In 2017, lawyers who were reinvestigating the case reached out to the analyst. He acknowledged that the statistical evidence was invalid. He said he should have indicated “that the hair sample found on the defendant could have come from the victim, and the hair sample found on the tablecloth used to cover the victim could have come from the defendant.” A new medical report also suggested that the charges were a product of a misunderstanding. The little girl wasn’t suffering from abuse, it concluded: She had a strep infection. Ms. O’Brien said bite mark analysis was even more bogus than hair comparisons. Often you can’t even tell if a wound is a bite mark, she said. “It doesn’t even get past the barest suggestion of scientific reality.” This pseudoscience cost Steven Chaney decades of his life. In 1987, Mr. Chaney was charged with murdering a couple who sold him drugs. At trial, a medical consultant testified that he’d compared a wax model of Mr. Chaney’s mouth to a mark on the male victim’s arm. Mr. Chaney’s upper and lower arches “matched” the bite, he said, adding that “only one in a million” people could have made that impression. In 2018, an appeals judge concluded that “scientific knowledge underlying the field of bite mark comparisons has evolved” since Chaney’s trial “in a way that contradicts the scientific evidence relied on by the State at trial.” Though this was an extreme example, Mr. Cole said, exaggerated odds are common. “Often they are just saying this person is the source of the bite mark or it’s practically impossible that they are not the source of the bite mark,” he said. He remains concerned that, even though this type of analysis has been widely disavowed by forensic scientists, “not one court in the entire United States has said that bite mark evidence shouldn’t be admissible in court.” DNA evidence analysis continues to be far more scientifically respected than the older methods of matching hair samples and bite marks, but the case of Mayer Herskovic is a reminder of how testimony about genetic odds can be misleading in court. In 2013, as a group of men was attacking a victim, an assailant grabbed the victim’s shoe and flung it onto a nearby roof. The genetic sample collected from the shoe was too small to be useful. But the Office of the Chief Medical Examiner in New York had developed software that it claimed could amplify samples. At trial, an expert testified that the probability that the shoe sample contained Mr. Herskovic’s DNA was 133 times greater than the likelihood that it came from an unknown person. He was convicted. Two years later, a higher court concluded that the expert witness had oversold this newfangled technique. Mr. Herskovic was exonerated. And the medical examiner’s office abandoned the amplification tool. By studying cases where individuals have been exonerated, we have been able to identify the main factors that contribute to wrongful convictions. At KWIP, we see these factors—often in combination—in the many applications that arrive in our mailbox from prisoners seeking our help. The leading factors in wrongful convictions are: Eyewitness MisidentificationEyewitness misidentification is one of the most common factors in cases of wrongful conviction. Nationally, 28% of all exonerations involve mistaken eyewitness identification. Social science research demonstrates that human memory is highly imperfect and fragile. When people experience a stressful event like a crime, they are much less able to make an accurate identification. Witnesses are even less accurate when they attempt to identify someone of another race. Additionally, lineups and photo arrays can be suggestive and lead a witness to pick the wrong person. This can happen when the suspect is the only person in an array who closely matches the description of the offender. Police officers can also influence the process by how they interact with a witness during the identification procedure. A police officer's comments, body language, and positive feedback can steer the witness towards a particular suspect and then inflate the witness's confidence in their identification. Despite study after study proving the unreliability of eyewitness identification, it is extremely persuasive evidence. When a crime victim points to the defendant in the courtroom and says with certainty, "That is the person who did this to me," juries are unlikely to reject that testimony.
False ConfessionsFalse confessions have been a factor in 12% of proven wrongful convictions nationwide. While it may seem difficult to understand why someone would confess to a crime they did not commit, there are many reasons that this can happen. For instance, physical intimidation or threats of violence by law enforcement can lead a suspect to falsely confess. Common interrogation techniques can also be psychologically coercive. For example, police are allowed to lie about the evidence and make a suspect believe that forensic testing or other conclusive evidence has already proven their guilt, even when this is not true. Police might also provide false assurances that things will go better -- and a long interrogation will finally cease -- only if the person confesses. The truth is that many people break under this pressure, especially when the interrogation is lengthy or when they've been deprived of food, water, and/or sleep. Young people and people with intellectual disabilities are especially vulnerable to giving a false confession.
Police and Prosecutorial MisconductOfficial misconduct by police officers, prosecutors, or other government officials has been present in 54% of wrongful convictions across the nation. Because criminal cases have many different stages, official misconduct can occur in numerous ways. At the investigation stage, police engage in misconduct when they deliberately use suggestion in an identification procedure, coerce a witness to implicate a suspect, fabricate physical evidence, or use improper interrogation techniques to secure a confession. At the trial stage, prosecutors corrupt the process when they conceal exculpatory evidence (i.e., evidence favorable to the defendant) or when they introduce false or perjured testimony.
False and/or Misleading Forensic EvidenceFalse or misleading forensic evidence has been a contributing factor in 24% of exoneration cases across the country. Most forensic disciplines were developed within law enforcement and have not been subject to the kind of rigorous testing normally conducted to validate a scientific theory. As the forensic sciences have come under greater scrutiny, some disciplines -- including bitemark analysis and microscopic hair comparison -- have been exposed as nothing more than junk science. Even in more reliable disciplines, experts often overstate their results and fail to acknowledge the limitations or error rate of a particular forensic technique. Finally, like everyone, forensic practitioners can make mistakes, including mixing up samples or contaminating specimens. In some cases, forensic analysts have fabricated results, hidden exculpatory evidence, or reported results when testing had not been conducted.
Witness PerjuryFalse accusation or perjury is the most common feature of wrongful convictions and has been a factor in 60% of documented exonerations. Most often, witnesses lie because they receive some benefit for testifying against the defendant. For example, a person in jail facing criminal charges can secure a favorable plea bargain, dismissal of their own charges, special privileges in jail, or even money by offering damning evidence against a fellow inmate. These benefits create a strong incentive to lie. In many wrongful convictions, defendants were not given key information related to the credibility of the incentivized witnesses who testified against them, including the exact benefits received, the witness's history of cooperating in other cases, and the witness's criminal history.
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