The first time the words appeared, it was in an amicus brief filed in Williams v. Illinois.  Criminal defense lawyers were, to be mild, giddy about it, and could barely contain their delight that New York County District Attorney Cyrus Vance put in writing that the foundations of so many convictions, eyewitness identifications and confessions, were unreliable.

The expectation was that we would never see these words again. Maybe it was a mistake.  Maybe it was an inartful argument.  But we held the words close to our breast because the notion that this would happen again was, well, more than any lawyer could expect.  We were wrong.

In an Op-ed in the New York Times, Cy Vance did it again.

No law enforcement tool is perfect, and, as with a fingerprint, a DNA match at a crime scene is an investigative tool, not proof positive of guilt. But DNA is by far the most reliable evidence we have today — more than eyewitness accounts, testimony and even confessions. And importantly, as we try to make our justice system more fair, DNA is truly color blind.

This paragraph concluded his argument in favor of collecting DNA from “every person convicted of a crime,” meaning from those convicted of misdemeanors now exempt from collection. He argues that in the case of Curtis Tucker, it would have prevented a crime from occurring by solving an open case years earlier.  One anecdote, of course, makes for a low rent argument, but people find concrete examples easier to grasp than theoretical explanations.

His proposal is relatively modest, given that others argue for the collection of DNA from every person arrested, rather than convicted.  Still, issues abound.

Crucially, DNA evidence does more than put criminals away; it also exonerates the innocent. One of my top goals as district attorney has been to avoid wrongful convictions. Having a tool like an all-crimes DNA databank at our disposal would go a long way toward helping us achieve that all-important goal of avoiding wrongful convictions.

Cy has a point, as we’ve learned from the excellent work of the Innocence Project.  It is most definitely a two-way street, with  prosecutors like John Bradley fighting to prevent the DNA testing that exonerated Michael Morton. 

Despite the truly remarkable benefits of DNA testing, some skeptics have questioned whether it is sufficiently regulated and reliable. This concern is understandable but unfounded. The collection of DNA is highly regulated in the eight state-of-the-art, accredited state labs that conduct criminal forensic analysis. Strict safeguards control the handling of DNA testing and results, including the storage of information by barcode and not name, with criminal penalties for those who violate these rules. When testing leads to a match in the databank, samples are retested at least once and often twice. To date in New York, we have never had a “false positive,” or the misidentification of DNA from one person as the DNA of another.

Just down the road apiece from Manhattan is Nassau County, where the  crime lab was shut down for rampant impropriety.  The local DA, Kathleen Rice was shocked (shocked!), having no clue that anything was amiss.  So it hasn’t happened to Cy yet? That doesn’t mean it can’t. Or won’t. All the official words designed to make us feel secure in the handling of DNA, up to and including “barcode,” will mean little should a scandal happen.  Scandals do happen.  Even in New York City.

Today, DNA is the magic bullet of forensic science, the evidence that changes everything.  Fingerprints once held that status, but we’ve since learned that this “investigative tool” was another bit of evidence that was converted into infallibility by junk science.  And we’ve learned that eyewitness identifications, which “everybody knows” is incontrovertible, are remarkably unreliable.  And confessions, which “nobody would ever give if they didn’t do the crime,” are barely worth the paper they’re written on.

Cy Vance is right about much of what he writes.  He’s right that people have been convicted for centuries on evidence that was universally embraced and yet unreliable.  He’s right that the myth of “common sense,” that jurors, witnesses and his assistants, will cling to the traditional, albeit unreliable, evidence as if it’s sacred. 

But he’s not right that nothing can go wrong. DNA proved Amanda Knox guilty, and was subsequently shown to be wrong.  Whenever people are involved, and people are always involved in the prosecution of crime, something will go wrong. That it hasn’t gone wrong yet in New York County doesn’t mean it won’t. And when it does, if it does, someone will blame pilot error.

The op-ed, however, makes one thing clear for now.  It was no accident, no fluke, that Cy Vance’s amicus brief acknowledged that the best traditional evidence ever, the stuff used to convict more defendants than anything else, is unreliable.  This time, it comes directly from Cy’s hand. This time, following on earlier commentary noting the significance of his statements, it was as deliberate as it gets. Cy Vance confirmed that eyewitness identifications and confessions are not reliable.  Cy Vance knew what he was saying, and he said it. Again.

And for that, I thank him.