A federal judge has stunned prosecutors by ruling that fingerprint identification fails three of four standards set by the U.S. Supreme Court for scientific evidence. The ruling may open the way for challenges to the scientific status of ballistics and other forensic techniques as well.
In 1993 the U.S. Supreme Court clarified the Federal Rules of Evidence specifying what counts in court as science. In Daubert v. Merrell Dow Pharmaceuticals, the court said that a technique or methodology qualifies as science only if it can be tested, is subject to peer review, possesses known rates of error, and is generally accepted as science. In 20 different pretrial "Daubert hearings" in the past 3 years, defense lawyers and skeptics have argued unsuccessfully that fingerprint identification--the practice of matching a "latent print" found at a crime scene to a copy taken by authorities--does not satisfy the court's criteria. But for critics of fingerprinting, the 21st decision proved the charm.
On 7 January, Judge Louis H. Pollak of the U.S. District Court for the Eastern District of Pennsylvania ruled whether fingerprint evidence could be introduced in a murder trial in his court. He rejected the argument that the technique had been tested both by 100 years of courtroom experience and by examiners checking each other's findings. Fingerprint identification has not been subject to peer review, the judge found, in part because fingerprint examiners do not constitute a "scientific community." Pollak further found that the error attributable to the practitioner cannot be quantified because examiners decide subjectively whether a pair of prints match--as both supporters and critics of the method agree. Pollak ruled that both sides could discuss fingerprint evidence in the trial, but he forbade fingerprint examiners from declaring whether or not latent prints match those of the accused.
The decision sends a strong message to fingerprint examiners, says James Starrs, a law professor and forensic scientist from George Washington University in Washington, D.C. "Before you claim that you can match a print to the exclusion of all other fingerprints in the world, you better test it," says Starrs, who testified in an earlier Daubert hearing. But David Ashbaugh, a fingerprint examiner with Rideology Consulting Services in Hope, British Columbia, and a staff sergeant in the Royal Canadian Mounted Police, says that fingerprint identification is sound science that will survive the ruling. "This is just one judge. There will be opportunities to present [our arguments] to other judges," says Ashbaugh. Both Starrs and Ashbaugh expect defense attorneys to use the decision to question the scientific credibility of other forensic techniques such as ballistics and tool marking.