How does DNA evidence compare to eyewitness testimony?
DNA analysis garnered good press in the 1990s, when it exonerated people who were wrongly sentenced to life in prison. Suddenly, a drinking glass or comb had the potential to identify its user beyond a reasonable doubt. Paternity cases became open-and-shut, as did cases of forcible rape.(4) DNA analysis is extremely accurate.(3) Errors are so rare (1 in 10,000) that DNA, if available, is nearly always the most accurate method of identification. Problems with DNA analysis are nearly always low-tech, caused by a careless worker. Even a good lab has an error rate of 1 in 200, not because of inaccuracy in the DNA testing itself, but because, for example, samples are mislabeled or contaminated. This is not a problem if DNA tests are performed after there is reason to suspect a person. However, with the growth of DNA databases, the possibility now exists for someone to be accused based solely on DNA. This creates a measurable risk of a false identification. For example, processing a rape kit
