Identifying the needs of the forensic science in the U.S
The Honorable Harry T. Edwards
Senior Circuit Judge and Chief Judge Emeritus
United States Court of Appeals for the D.C. Circuit
With the exception of nuclear DNA analysis, however, no forensic method has been
rigorously shown to have the capacity to consistently, and with a high degree of certainty,
demonstrate a connection between evidence and a specific individual or source. Yet, for years, the courts have been led to believe that disciplines such as fingerprinting stand on par with DNA analysis.
For example, in a decision issued by the Seventh Circuit, the court reported that an FBI fingerprint expert had “testified that the error rate for fingerprint comparison is essentially zero.” In a later decision issued by the Fourth Circuit, that court cited the Seventh Circuit opinion approvingly, noting that an expert from the FBI had testified that the error rate for fingerprint comparison was “essentially zero.” The committee’s report rejects as scientifically implausible any claims that fingerprint analyses have “zero error rates.” A “zero error rate” is a myth in fingerprint analyses and in all other forensic disciplines. That is no surprise, however, because there is no such concept as a zero error rate in good scientific analysis. Of greater concern is the dearth of solid research to establish the limits and measures of performance and to address the impact of the sources of variability and potential bias in most disciplines.
Another serious concern is contextual bias. Some studies have demonstrated that
identification decisions on the same fingerprint can change solely by presenting the print in a different context. In one study, for example, fingerprint examiners were asked to analyze
fingerprints that, unknown to them, they had analyzed previously in their careers.
Contextual biasing was introduced – that is, examiners were told that the “suspect confessed to the crime” or the “suspect was in police custody at the time of the crime.” In one-third of the examinations that included contextual manipulation, the examiners reached conclusions that were different from the results they had previously reached.