How accurate (subjective) are fingerprints?
Thanks to Scott Benson at Grits for Breakfast for pointing out a story that provides more ammunition for attacking fingerprints. At a forensic conference sponsored by the Texas Court of Criminal Appeals Texas DPS fingerprint examiner Bryan Strong described how they resolve disputes among examiners. Here's the story related by Grits:
Mr. Strong described what happens when the first examiner finds a match but the verifying analyst doesn't agree. In such instances, he said, they notified their supervisor and all of them conferred to make a decision. A defense attorney in the crowd asked what seemed to me an obvious question: When two examiners originally disagreed but a supervisor resolved the issue in favor of a match, was that disagreement recorded in the final report? No, replied Strong, only the conclusion. At this, the audience began to murmur and fidget. Somebody from the back cried out, "Have you ever heard of Brady v. Maryland?," which is the US Supreme Court case requiring the state to turn over all exculpatory evidence to the defense before trial. No he had not, replied a credulous Strong, a statement which elicited an audible gasp from the crowd.
The Brady problems are obvious, and create a whole of host of potential issues. What struck me about the story however is that provides more evidence of just how unreliable - and unscientific - fingerprint examinations are. Despite what they want you believe, fingerprint examinations are nothing more than a subjective opinion. The fact that two examiners disagree shows that.
I've said it before, and I'll continue to say it: we need to challenge fingerprints more often. There is no science involved, and we need to keep pointing that out. While comparing inked prints to inked prints may be reliable and accurate, there is a big difference between an inked print and a partial print that you have only limited information on. This story gives us one more weapon in the arsenal.
