Are fingerprints bad science?
We are left with the question of whether fingerprint evidence is totally shoddy. The answer is: of course not. DNA exonerations have exposed a lot more bad serology and bad microscopic hair comparison than bad fingerprint evidence. In fact, post-conviction DNA testing has exposed more bad DNA evidence than bad fingerprint evidence. (There are practical reasons for this; unlike fingerprints, blood and hair are biological materials that can be DNA tested.) But it does mean that fingerprint evidence has an error rate. We are commonly told that even when errors do occur, they will be caught by a second examiner who verifies the match. But, in Cowans’ case, two fingerprint examiners testified that the print belonged to him. Defendants are permitted to hire their own fingerprint examiners to check the government’s work, and Cowans’ defense attorney hired two retired fingerprint examiners. These consultants, paid by the defendant, incorrectly con- firmed the prints as his. Sometimes the syste
