Back in 2004, Itiel Dror hit on a clever way to test the influence of outside information on the judgment of fingerprint experts. He took pairs of prints from the previous work of five fingerprint analysts, prints that they had testified were certain matches. Then he told the experts that these were the prints from the case of Oregon lawyer Brandon Mayfield, who was briefly arrested because his prints were thought to match one found during the investigation of the Madrid bombing. It was a perfect set-up: hey, expert, would you mind looking at these prints that the FBI thought matched, but which turned out to be an error? Would you have made that same mistake or not?
Only one of the experts stuck by his previous judgment and said the prints were a match. Three reversed themselves and one said the results were "inconclusive."
Only the last was honest.