Forensic Evidence Isn’t As Reliable As You Might Think

CREDIT: Associated Press/Hal Yeager

Anthony Ray Hinton was released from death row in April, after nearly 30 years behind bars.

Earlier this month, former death row inmate Beniah Dandridge was exonerated and freed after spending 20 years in prison. Dandridge was convicted for murder when three examiners claimed his fingerprints matched prints found at the crime scene. In reality, the fingerprints were not his, and strong evidence suggests they actually belonged to the victim’s son.

Anthony Ray Hinton, another death row inmate in Alabama, was similarly exonerated and released in April. His conviction for the murders of two restaurant managers during a string a robberies hinged on ballistics evidence. A gun found at his home was linked to bullets found at three robbery locations, and Hinton was sentenced to die. But in 2014, the Supreme Court called for a new trial, and three experts testified that the bullets found at the crime scenes did not actually match each other. The examiners concluded that the previous ballistics results were botched, and Hinton was freed after spending 30 years in prison for a crime he did not commit.

Sadly, neither story is an anomaly. For decades, flawed forensic evidence has been used to convict innocent people like Dandridge and Hinton. And across the country, courts and officials refuse to re-examine questionable cases.

Beniah Dandridge, right, is released from death row after 20 years behind bars.

Beniah Dandridge, right, is released from death row after 20 years behind bars.

CREDIT: Associated Press/Kim Chandler

If you were to judge the criminal justice system based on TV shows like Law and Order or CSI, you might think forensic evidence is conclusive proof of a person’s guilt. Reality is much messier. DNA is widely considered an accurate indicator of a defendant’s involvement in a crime, but prosecutors also turn to less trustworthy evidence, including hair microscopy, bite mark comparisons, firearm tool mark analysis and shoe print comparisons. There is little research to suggest that forensic matches are scientific and infallible.

The FBI and DOJ recently admitted that hundreds of convictions involved flawed hair comparisons, even though research about how common it is for different people’s hair to look the same does not exist. Similarly, there are no scientific studies proving that individuals have unique fingerprints or dental prints. There are no guidelines to determine a match between a shoe print found at a crime scene and that of a suspect. And there is no proof that bullet marks are uniquely connected to a specific firearm.

But according to Senior Attorney Charlotte Morrison of the Equal Justice Initiative, who worked on Dandridge and Hinton’s court challenges, forensic science is not the only problem that arises during an investigation. Evidence is problematic, but so are the examiners who rely on it. Morrison pointed out that certain protocols are crucial to make reliable findings, but examiners do not necessarily follow them.

“It’s the kind of gross overstatement that we know leads to unreliable convictions: saying that fingerprint evidence is infallible, that a match is an indisputable thing like a bar code,” she told ThinkProgress. “Examiners are trained to not give that type of testimony because of the risk of producing unreliable convictions, but we see that time and time again. Where men and women are wrongfully convicted, the examiners’ statements are over the top in terms of their reliability and their confidence level.”

Studies also show that examiner biases play a significant role in the collection of evidence and the assessments that they make. In many cases, forensic experts are motivated to reach certain conclusions, because they are offered rewards or face pressure from law enforcement and prosecutors to do so. Some people make assessments based on cognitive bias, meaning their conclusions are based on what they anticipate the findings will be. Others demonstrate confirmation bias, meaning they report findings that align with their personal opinions about a case.

Biases against specific groups of people also come into play.

One of the most egregious cases Morrison is familiar with involved the dehumanization and imprisonment of a woman because she was poor. In 2007, Marsha Colby gave birth to a stillborn. However, a forensic pathologist botched the autopsy and claimed Colby killed her newborn child, despite no evidence that the baby was born alive. Colby was sentenced to die until additional forensic experts re-examined the evidence and concluded the original pathologist lied.

“This directly deals with poverty and how poor mothers are demonized and criminalized in the system,” she said. “This willingness to call this tragic loss of a baby a homicide and to blame the mother is only possible if you see poor women, women who are struggling, as something less than. That’s what happened in this case. She was not seen as fully human when the examiner arrived at her home.”

Despite the fact that certain types forensic evidence are imperfect, as well as the people who collect and present that evidence, officials remain reluctant to re-examine cases.

“Even with science that is established and accepted in the courts, there’s been a failure to take the code of ethics that governs experts seriously,” Morisson said. “In our political climate, finality is valued more than accuracy. To acknowledge a mistake is typically seen as weakness.”

As a result, courts have made it extremely difficult for people to appeal convictions based on flawed forensics. The standards to claim innocence are impossibly high. In Alabama, for instance, a defendant has to be able to prove that there is absolutely no evidence linking you to a crime, in order to be found innocent. But if someone or something ties a defendant to an offense in any way, the innocence claim is dismissed altogether and the defendant is barred from pursuing an innocence claim.

According to Morrison, the key to ensuring wrongful convictions are examined thoroughly is to task neutral actors, such as Conviction Integrity Units, with assessing cases. Forensics experts should also be assigned to defendants, because many people cannot afford their own — which costs them a case.

“We need prosecutors and state officials who are willing to prioritize justice, fairness, and reliability — and acknowledge mistakes when they happen,” she said. “In Mr. Hinton’s case, it’s been 16 years since we presented the evidence and asked the state to look at the evidence that exonerated [him]. And yet, to this day, we have not had any state official who’s been willing to talk about that.”