Verdict on Forensic Science: It's Quite Bad

By Rachel Cernansky | February 20, 2009 2:16 pm

forensic.jpgForensic science, often used to produce evidence for criminal trials using such techniques as fingerprint analysis, is “badly fragmented” and unreliable in the U.S., according to a report by the National Academy of Sciences. Crime laboratories around the country are grossly underfunded, lack a scientific foundation and are compromised by critical delays in analyzing physical evidence…. The report calls into question the scientific merit of virtually every commonly used forensic method, including analysis of fingerprints, hair, fibers, blood spatters, [and] ballistics [The New York Times].

According to the report “no forensic method”—with the notable exception of DNA analysis—”has been rigorously shown able to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.” Of particular concern is the use of comparative forensic methods like hair or fingerprint analysis to match a piece of evidence to a particular person, weapon, or place [New Scientist].

DNA was excluded from the criticism because “the chances of a false positive are minuscule, but also because the likelihood of such errors is quantifiable. Studies have been conducted on the amount of genetic variation among individuals, so an examiner can state in numerical terms the chances that a declared match is wrong.” Other forensic techniques, however, have not been studied to determine how many sources might share similar features, or to quantify the level of uncertainty in any measurement made.

The disciplines based on biological or chemical analysis, such as toxicology and fiber analysis, generally hold an edge over fields based on subjective interpretation by experts, such as fingerprint and toolmark analysis…. Claims that [fingerprint] 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 [National Academy of Sciences]. The report added that while some tests may not be precise enough to identify an individual, they can help to narrow the pool of suspects or possible weapons. Microscopic hair analysis, for example, cannot reliably match a hair with one particular individual, but it can help to identify a subpopulation as plausible suspects or not.

The report issued recommendations, including that the use of forensic evidence in criminal trials be contingent upon both the foundation of a reliable scientific methodology, as well an allowance for human error or bias during interpretation. Testimony using forensic science should also be required to acknowledge a lack of certainty due to imperfect testing or analysis. The study also recommended that an agency, to be called the National Institute of Forensic Science, be created and be independent of the Justice Department, which has traditionally been the nation’s primary forensics research agency. Crime laboratories should be managed separately from police departments to ensure that their findings are protected from bias [The New York Times].

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Image: Flickr / Ryan Gessner

  • Charles Schmidt

    The fact that Forensic science is presented as being able to give all answers with out error is aided by television. But the fact remains that being part of an agency they may look for things or directed too that could be called evidence to support a preconceived idea or suspect and therefore not be objective. How qualified are those that do the job, is there a standardized test to see what they know and can do? We may have came a long way in that line of evidence but we do not have all the answers that some and that includes those in the job think there is.

  • YouRang

    The annoying part of reports like NAS’s is that fingerprints e.g. might not be good evidence if it was derived to support an accusation (in the same way that a photo identification is not good if presented to a witness by itself rather than in a lineup of very similar others); but it should suggest a possible perp who no one had thought of and other corroboration verified the guilt. IOW they shouldn’t be comparing fingerprints to known suspects–they should be comparing fingerprints to a database (or a reasonable subset).

  • nick

    And this goes right along with what this criminal justice professor (and former public defender) and police detective have to say about the criminal justice system. The upshot is: never talk to the police. Notice how the Miranda rights read to you say “everything you say can and will be used AGAINST you in a court of law.”

    If forensic evidence was so great, there’s no reason DNA evidence would be getting innocent men taken off of death row.

    Justice, as they say, is blind.

  • Bill Kurtis

    Forensic science is not the only area of our justice system that is suspect, but this being the topic at hand let me say this; yes, justice is blind,but it need not be deaf, dumb,and stupid as well. One of the great misuses of the forensic information is to presure people that have not been proven guilty of anything into accepting a plea agreement.They thereby must assume guilt, simply because trying to mount a defense against squewd forensic evidence and a jury base so overwhelmed with televisions insistance upon the perfection of these forensic proceedures and techniques, that any attempt seems futile. The justice community and the forensics community see this as a great leap forward, when in fact if they would listen to the evidence and discuss its true wieght in proving the guilt or innocence of an individual, they may not be as quick to to jump to conclusions as they are. At one time the inteligent people of the world insisted it was flat and wouldn’t hear otherwise; things are not always as they first appear.

  • DrPDNA

    DNA profiling would appear to have a high degree of certainty, but is far from the truth. There have been circumstances such as Low Copy Number DNA profiling has wrongly typed suspects such as Sean Hoey & Wayne O’Donoguhue because of a lack of thorough interpretation of these results. Furthermore, false positive results of individual DNA testing laboratories are not readily available, so it is difficult to assess quality control procedures of these establishments. False positives rates of other diagnostic laboratories are more readily available. Thus DNA forensic analysis should also be criticized in the report.

  • DocDiggs

    There needs to be national standards for CSI (who should NOT be cops) and lab people and a national exam for licensing of personnel. With that said, I firmly believe that police, prosecutors, and judges care not one bit if the labs come back with accurate and reliable results or faulty or totally false results. These people and groups are not interested in justice (a finding of “guilty”is not necessarly justice), they care only in winning cases and possible innocence is not something they are interested in. I suspect that messed up lab results make their job of condemnation easier and so what if they are wrong…they won the case, right?


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