Forensic science in The U.S. needs an overhaul.

Many professionals in the forensic science community and the medical examiner system have worked for years to achieve excellence in their fields, aiming to follow high ethical norms, develop sound professional standards, and ensure accurate results in their practice. But there are great disparities among existing forensic science operations in federal, state, and local law enforcement agencies. The disparities appear in funding, access to analytical instruments, and availability of skilled and well-trained personnel; and in certification, accreditation, and oversight. This has left the forensic science system fragmented and the quality of practice uneven. Except in a few states, forensic laboratories are not required to meet high standards for quality assurance, nor are practitioners required to be certified. These shortcomings pose a threat to the quality and credibility of forensic science practice and its service to the justice system, concluded the committee.
There is some evidence that fingerprints are unique to each person, and it is plausible that careful analysis could accurately discern whether two prints have a common source, the report says. However, claims that these analyses have zero-error rates are not plausible; uniqueness does not guarantee that two individuals' prints are always sufficiently different that they could not be confused, for example. Studies should accumulate data on how much a person's fingerprints vary from impression to impression, as well as the degree to which fingerprints vary across a population. With this kind of research, examiners could begin to attach confidence limits to conclusions about whether a print is linked to a particular person.

Disciplines that are too imprecise to identify an individual may still be able to provide accurate and useful information to help narrow the pool of possible suspects, weapons, or other sources, the report says. For example, the committee found no evidence that microscopic hair analysis can reliably associate a hair with a specific individual, but noted that the technique may provide information that either includes or excludes a subpopulation.
In addition to investigating the limits of the techniques themselves, studies should also examine sources and rates of human error, the report says. As part of this effort, more research should be done on "contextual bias," which occurs when the results of forensic analysis are influenced by an examiner's knowledge about the suspect's background or an investigator's knowledge of a case. One study found that fingerprint examiners did not always agree even with their own past conclusions when the same evidence was presented in a different context.

Link: http://www8.nationalacademies.org/onpinews/newsitem.aspx?RecordID=12589