FBI, DOJ And Their Forensic Scientists State They’ll Continue Using Discredited Junk Science To Put People Behind Bars
The questions that DNA analysis had raised about the scientific validity of traditional forensic disciplines and testimony based on them led, naturally, to increased efforts to test empirically the reliability of the methods that those disciplines employed. Relevant studies that followed included:
• a 2002 FBI re-examination of microscopic hair comparisons the agency’s scientists had performed in criminal cases, in which DNA testing revealed that 11 percent of hair samples found to match microscopically actually came from different individuals;
• a 2004 National Research Council report, commissioned by the FBI, on bullet-lead evidence, which found that there was insufficient research and data to support drawing a definitive connection between two bullets based on compositional similarity of the lead they contain;
• a 2005 report of an international committee established by the FBI to review the use of latent fingerprint evidence in the case of a terrorist bombing in Spain, in which the committee found that “confirmation bias”—the inclination to confirm a suspicion based on other grounds—contributed to a misidentification and improper detention; and
• studies reported in 2009 and 2010 on bitemark evidence, which found that current procedures for comparing bitemarks are unable to reliably exclude or include a suspect as a potential biter.
Beyond these kinds of shortfalls with respect to “reliable methods” in forensic feature-comparison disciplines, reviews have found that expert witnesses have often overstated the probative value of their evidence, going far beyond what the relevant science can justify. Examiners have sometimes testified, for example, that their conclusions are “100 percent certain;” or have “zero,” “essentially zero,” or “negligible,” error rate. As many reviews—including the highly regarded 2009 National Research Council study—have noted, however, such statements are not scientifically defensible: all laboratory tests and feature-comparison analyses have non-zero error rates.