NEW VOICES: Scientific Experts Say DNA Evidence Not ​“Infallible”

Scientists who are skeptical of Massachusetts Governor Mitt Romney’s claim that DNA is “infallible” evidence in a death penalty case have voiced concern about the assumption, noting that there is no way to avoid all possible instances of human error and that the evidence does not always prove a person’s guilt or innocence. Theodore D. Kessis is the founder of Applied DNA Resources, based in Columbus, Ohio, and a faculty member at the John Hopkins School of Public Health in Baltimore. He provides expert testimony and analysis to the legal community, including reviews of protocols used by labs that analyze DNA evidence, and notes, “[L]ike anything that involves humans, there is always the possibility of error in DNA testing. I would not go so far as to say that DNA is foolproof. The spectrum of a DNA test may range from foolproof to something’s wrong here. DNA testing is a tool, and how that tool is used in a criminal trial may depend upon what you are trying to prove. Don’t misunderstand me, DNA is an invaluable tool. But in and of itself, DNA cannot tell you who committed a crime.” Dean Wideman, a forensic scientist from Texas, echoed Kessis’s concerns and noted that DNA evidence has its limitations. “DNA evidence has been used to acquit as often as convict… What it doesn’t tell us is the stuff that lawyers are good at using – it doesn’t tell us whether semen left is the result of rape or consensual sex. It doesn’t tell us what time a person was at a scene. It does not tell us why a person was at a scene… For all we hear about DNA evidence, oftentimes it is not going to move a case in one direction or another,” he said. (Cape Cod Times, May 6, 2004) See New Voices. See also, Innocence.