United States v. Davis

Earl Davis (defendant) was charged with robbery and murder after DNA on a getaway car's steering wheel and on a hat left at the scene matched his profile in a nationwide database -- a "cold hit," since no other evidence had linked him to the crime beforehand. The testing lab concluded, absent an identical twin, that Davis was the source of the DNA to a reasonable degree of scientific certainty, using a threshold of less than a 1-in-300-billion random-match probability. Davis moved to exclude the DNA evidence, arguing that scientists disagree on which of three valid methodologies best calculates the probability that a cold-hit match is random, and that source-attribution statements should be categorically inadmissible.