Ramblings & ephemera

Court acceptance of forensic & biometric evidence

From Brendan I. Koerner’s “Under the Microscope” (Legal Affairs: July/August 2002):

The mantra of forensic evidence examination is “ACE-V.” The acronym stands for Analysis, Comparison, Evaluation, and Verification, which forensic scientists compare with the step-by-step method drilled into countless chemistry students. “Instead of hypothesis, data collection, conclusion, we have ACE-V,” says Elaine Pagliaro, an expert at the Connecticut lab who specializes in biochemical analysis. “It’s essentially the same process. It’s just that it grew out of people who didn’t come from a background in the scientific method.” …

Yet for most of the 20th century, courts seldom set limits on what experts could say to juries. The 1923 case Frye v. United States mandated that expert witnesses could discuss any technique that had “gained general acceptance in the particular field in which it belongs.” Courts treated forensic science as if it were as well-founded as biology or physics. …

In 1993, the Supreme Court set a new standard for evidence that took into account the accelerated pace of scientific progress. In a case called Daubert v. Merrell Dow Pharmaceuticals, the plaintiffs wanted to show the jury some novel epidemiological studies to bolster their claim that Merrell Dow’s anti-nausea drug Bendectin caused birth defects. The trial judge didn’t let them. The plaintiff’s evidence, he reasoned, was simply too futuristic to have gained general acceptance.

When the case got to the Supreme Court, the justices seized the opportunity to revolutionize the judiciary’s role in supervising expert testimony. Writing for a unanimous court, Justice Harry Blackmun instructed judges to “ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable.” Daubert turned judges into “gatekeepers” responsible for discerning good science from junk before an expert takes the stand. Blackmun suggested that good science must be testable, subject to peer review, and feature a “known or potential rate of error.” …

There are a few exceptions, though. In 1999, Judge Nancy Gertner of the Federal District Court in Massachusetts set limits on the kinds of conclusions a handwriting expert could draw before a jury in United States v. Hines. The expert could point out similarities between the defendant’s handwriting and the writing on a stick-up note, the judge said, but she could not “make any ultimate conclusions on the actual authorship.” The judge questioned “the validity of the field” of handwriting analysis, noting that “one’s handwriting is not at all unique in the sense that it remains the same over time, or unique[ly] separates one individual from another.”

Early this year, Judge Pollak stunned the legal world by similarly reining in fingerprint experts in the murder-for-hire case United States v. Plaza. Pollak was disturbed by a proficiency test finding that 26 percent of the crime labs surveyed in different states did not correctly identify a set of latent prints on the first try. “Even 100 years of ‘adversarial’ testing in court cannot substitute for scientific testing,” he said. He ruled that the experts could show the jury similarities between the defendants’ prints and latent prints found at the crime scenes, but could not say the prints matched. …

… the University of West Virginia recently offered the nation’s first-ever four-year degree in biometrics …

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