DNA testing may be the only part of forensic science that’s actually scientific

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Forensic science—the ‘science’ we use to gather evidence after a crime to help determine a person’s legal fate—is deeply flawed. In fact, of the many tools of forensic science such as bloodstain pattern analysis, fingerprinting and hair analysis, only DNA testing seems to hold up to scientific scrutiny.

Slate’s Mark Joseph Stern writes: “Far from an infallible science, forensics is a decades-long experiment in which undertrained lab workers jettison the scientific method in favor of speedy results that fit prosecutors’ hunches.”

His criticism is backed by a 2009 report from the National Academy of Sciences. Chemical & Engineering News’s May cover story follows up on this report, and it is largely discouraging. In the five years since the NAS found serious, systemic problems in forensic science almost nothing has been done. Only just now have two federal oversight bodies been established by the Department of Justice and the National Institute of Standards & Technology to attempt to at least begin the long process of overhauling the system.

Aside from DNA testing, which—when conducted properly (more on this in a moment)—was deemed scientifically sound by the original NAS report, almost every other technique used by forensic science has been called into question. From Chemical & Engineering News:

“Fingerprint analysis, a staple of many forensics cases, is the most commonly cited example: No study has ever shown that every individual has unique fingerprints or defined what is needed to ensure that two fingerprint samples match.”

If this revelation comes as a shock, you’re not alone. I was shocked, and we’re all under the spell of what is now called the CSI Effect. Basically, we’ve been exposed to so many procedurals in which forensic science is presented as infallible that all we have to hear is a bit of scientific-sounding terminology like “bite-mark analysis” and we tend take the conclusions as gospel. Stern opens his piece with the story of Earl Washington:

Nine days before death row inmate Earl Washington’s scheduled execution, his lawyers informed the state of Virginia that it was about to murder an innocent man. Forensic analysis of semen introduced at trial had convinced the jury that Washington, whose mental abilities matched those of a 10-year-old, had brutally raped and murdered a young woman in 1982. Washington’s lawyers uncovered evidence that the analysis was faulty. The state halted the impending execution, and following a gubernatorial pardon, Washington was released from prison in 2001. He had been there for 17 years.

Not everyone is so lucky. Journalist David Grann, writing for the New Yorker in 2009, penned a particularly chilling account of a likely innocent man sent to his death for arson when, it turns out, the entire arson investigation ‘discipline’ used to condemn him was little more than a tradition of hearsay and pseudoscience. Grann’s piece is long, but worth reading in full to get a real taste of the wide, potentially deadly discrepancies between what outside scientists have to say in crimincal cases versus what the law-appointed forensics “experts” have to say.

So we’re left with the tenuous hope that at least DNA is a reliable piece of evidence—but this assumes that DNA evidence will be properly collected, cataloged, and tested. Even five years after the NAS called into question untold numbers of convictions, it’s still incredibly difficult for convicts to get access to DNA testing when they need it.

An Innocence Project’s fact-sheet reveals just how difficult it can be for convicts to gain access to the one truly scientific test available to exonerate them. Though all states have some laws ensuring access to post-conviction DNA testing, these laws are woefully inadequate. Some of the shortcomings listed by the Innocence Project include:

• Some laws present insurmountable hurdles to the individual seeking access, putting the burden on the wrongfully convicted person to effectively solve the crime and prove that the DNA evidence promises to implicate another individual.

• Despite the fact that approximately 30% of the nation’s 311 wrongful convictions proven by DNA involved a false confession, admission, or guilty plea, certain laws still do not permit access to DNA when the defendant originally pled guilty or confessed to the crime.

• Many laws fail to include adequate safeguards for the preservation of DNA evidence.

• Several laws do not allow individuals to appeal denied petitions for testing.

• A number of states fail to require full, fair and prompt proceedings once a DNA testing petition has been filed, allowing the potentially innocent to languish interminably in prison.

They offer the example of Bruce Godschalk, who spent 15 years in jail on a wrongful conviction and seven of those fifteen years fighting to access the DNA evidence that eventually exonerated him.

The problems with our forensic science goes beyond mere scientific accountability; legitimate tests mean nothing if they’re not available when they’re needed. This is a moral imperative, not merely a scientific one: we need to clean up our forensic science system. The establishment of bodies for oversight is encouraging, but it’s hard to take it as anything more than cold comfort. As Stern puts it:

Our national experiment in untested forensics may soon be coming to a close. But it hasn’t ended in time to prevent a few more people like Earl Washington from being sacrificed on the altar of pseudoscience.”

Kenrick Vezina is Gene-ius Editor for the Genetic Literacy Project and a freelance science writer, educator, and naturalist based in the Greater Boston area.

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