Passage A

In this appeal of his criminal conviction, the defendant challenges the fingerprint evidence used against him at trial, claiming that fingerprint identification theory has not been adequately tested. He cites the inability of the fingerprint examiner who incriminated him at trial to name any studies establishing that no two persons have identical fingerprints.

The defendant claims that there are no established error rates revealing how often fingerprint examiners incorrectly identify a fingerprint as a particular person's, and asserts that fingerprint examiners lack uniform, objective standards. He cites testimony given by the fingerprint examiner at trial that there is no generally accepted standard regarding the number of "points of identification" required for a positive identification.

Although fingerprint identification has not attained the status of scientific law, it has been used in criminal trials for 100 years, and experts have long concurred about its reliability. While further testing and the development of even more consistent standards may be desirable, this court sees no reason to reject outright a form of evidence that has so ably withstood the test of time.

While it may be true that different agencies require different degrees of correlation before permitting a positive identification, fingerprint examiners are held to a consistent "points and characteristics" approach to identification. As the fingerprint expert testified at the defendant's trial, examiners are regularly subjected to testing and proficiency requirements, and uniform standards have been established through professional training and peer review. The trial court below was therefore within its discretion in crediting testimony that fingerprint identification has an exceedingly low error rate.

Passage B

Fingerprint examiners lack objective standards for evaluating whether two prints "match." There is simply no consensus about what constitutes a sufficient basis for identification. Some examiners use a "point-counting" method that entails counting the number of similar "ridge" characteristics on prints, but there is no fixed requirement about how many points of similarity are needed, and local practices vary. Others reject point counting for a more holistic approach. Either way, there is no generally agreed-on standard for determining precisely when to declare a match.

Although we know that different individuals can share certain ridge characteristics, the chance of two individuals sharing any given number of identifying characteristics is unknown. How likely is it that two people could have four points of resemblance, or five, or eight? Moreover, fingerprints used in forensic identification are typically partial and smudged. Are the odds that two partial prints from different people will match one in a thousand, one in a million, or one in a billion? No fingerprint examiner can answer such questions decisively, yet the answers are critical to evaluating the value of fingerprint evidence.

The error rate for fingerprint identification in actual practice has received little systematic study. How often do fingerprint examiners mistakenly declare a match? Although some proficiency tests show examiners making few or no errors, these tests have been criticized as lax; a more rigorous test showed a 34 percent rate of erroneous identification.