Forensic science is often lacking

Scientific evidence is often lacking scientific rigor

In many criminal cases, the lynchpin of the prosecution's case is often physical evidence. Such evidence may tie an individual to a particular place or to having contact with another individual. In drug cases, it may decide the ultimate outcome of the case because if a kilo of white powder is not an illegal drug, the majority of the other events related to the charges are insignificant.

This forensic evidence is vetted for the courts by crime labs in every state. For many people, the image of television's "CSI" may come to mind. Troublingly, in many crime labs, the truth may be closer to bumbling, incompetent and even corrupt operations that compromises much of the quality of the work done in these labs.

In addition, this issue opens the broader question of the reliability some types of forensic evidence. For decades, courts have allowed forensic evidence that has had little scientific backing. The analysis in many states of arson investigations or testimony supporting bite-marks or hair matching has shown very little or no scientific research that would allow the claims that are made in court to be considered valid.

DNA evidence changed the standard

In many ways, some of these problems have become known because of the use of DNA evidence. Properly done, DNA evidence often employed in sex crime cases can determine conclusively if an accused committed a crime.

The apparent scientific certainty of DNA evidence has led to hundreds of exonerations and raised questions concerning the validity and reliability of other types of forensic tests. Examinations of bite marks, scrapes from tools on surfaces, matching of hair or carpet fibers has long been presented as "science."

Recent studies have been critical of these methods and found them lacking in scientific basis. Unfortunately, many individuals have been convicted and sent to prison on this type of evidence.

Two elements necessary

There are two issues when reviewing the validity of forensic evidence. First is the issue of scientific validity. The test should have some scientific support for the assertions it can make. DNA has this basis. Given a sufficiently sized sample of human cells, proper preparation and testing by a trained and qualified technician, a DNA test can produce a virtually certain identification or similarly, rule out a match.

And the qualifiers in that last paragraph lead to the second element that is necessary even when a scientifically valid test is performed. The evidence must provide enough material to provide a testable sample, and it must be properly handled to prevent damage or contamination by a qualified technician to ensure the validity of the result.

In some cases, like bite mark analysis or fiber matching, there may be neither scientific basis nor the rigorous implementation of testing procedures. Unlike a valid scientific test, much of this analysis can vary depending on the "expert" who provided the report or testimony.

DOJ requires certification

The department of Justice has announced it will require the crime labs it uses to obtain certification. This is a step in the right direction, but will hardly solve many of these problems. It only addresses the second element of forensic testing validity and even that is somewhat nominal.

Unfortunately, certification of crime labs is not governed by federal standards, and can vary among groups that perform certifications. The lack of uniformity, scientific rigor and enforcement also undercut the value of this certification.

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