The New York Civil Liberties Union featured experts in genetic science and criminal justice at an Albany news conference on a new and controversial technique that involves the collection of DNA from family members of an individual whose DNA is a near – but not precise – match with DNA evidence found at a crime scene.

The New York State Commission on Forensic Science has been considering the use of “partial match” DNA evidence over the past year. The issue is on a proposed agenda of the commission’s upcoming meeting scheduled later this month.

At the news conference the experts warned against proceeding with familial searching, if at all, without considering the potential harm both to individuals and to the credibility of law enforcement.

Under current law, DNA evidence from a crime scene is compared against DNA samples in the state databank, which have been taken from individuals who have been previously convicted of certain crimes. When a DNA sample in the state databank matches crime-scene DNA, the individual from whom that sample was taken is usually considered a suspect.

But what if the crime-scene DNA is a near match with a DNA sample in the state’s databank? A near match – or “partial match” – between a crime-scene sample and the DNA of someone in the state’s databank may implicate a blood relative of that person. This is the scientific rationale for obtaining DNA from blood relatives of the individual whose DNA is a partial match with DNA found at a crime scene.

“Mining the database for partial matches is a radical departure from the original intent in establishing a forensic DNA database,” said Tania Simoncelli, science advisor to the American Civil Liberties Union. “A move in this direction would undermine principles of privacy and fairness by placing scores of innocent people under lifelong genetic surveillance simply because they have a relative who has been convicted of a crime.”

The speakers asserted that while the use partial-match searching techniques may have a statistical basis, these techniques raise fundamental questions related to the potential for error and abuse in the handling of DNA; the adequacy of judicial oversight and protections of due process; racial disparities in the investigation and prosecution of alleged criminal conduct; and the potential for including substantial numbers of innocent people in the DNA databank.

“The idea that forensic science is so precise that a false match between a sample and a suspect is a one-in-a-billion occurrence is science fiction,” said Troy Duster, professor of sociology at New York University. “This is the ‘CSI effect’ – it causes us to overestimate the precision of the science, and underestimate the incidence of human error.”

The NYCLU’s legislative director Robert A. Perry stated that “authorization of so-called familial searching based on partial-match DNA would require legislative action. This use of forensic DNA is not authorized under existing state law.”

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