A Chicago Tribune investigation of forensics in the courtroom turned up evidence of questionable science, flawed analysis, and shoddy lab practices that sometimes undermine the quest for justice. Long considered unbiased and untainted, crime labs and analysts are facing new scrutiny and tough questions about their accuracy.At the center of this upheaval is DNA testing. Of 200 DNA and death row exoneration cases nationwide in 20 years, mre than a quarter–55 cases with 66 defendants–involved forensic testing or testimony that was flawed.
Among the Tribune’s findings in a five-part series: Fingerprinting is so subjective that the most experienced examiners can make egregious mistakes. Prosecutors continue to rely on experts who embrace debunked theories about arson. Forensic dentists, who link suspects to bite marks left on crime victims, continue to testify despite having no accepted way to measure their rate of error or the benefit of peer review. Scandals at various labs have spotlighted analysts who have incorrectly assessed evidence, hidden test results helpful to defendants and testified falsely in court. Experts often express certitude based on an unfounded confidence in their forensic specialty and their ability to practice it. “I have no problem with forensic science. I have a problem with the impression that’s being given that those disciplines can make an absolute identification of someone, and that’s not the case,” said Terrence Kiely, a DePaul University law professor and author of “Forensic Evidence: Science and the Criminal Law.” “It’s the white coat-and-resume problem,” he added. “They’re very, very believable people. And sometimes the jurors will take [their testimony] as a `yes,’ where the science can only say it’s a `maybe.'”