Saturday, 17 May 2008

getting csi right

Since its debut eight years ago, CSI: Crime Scene Investigation has been credited with an increased interest in and knowledge of forensic science. Enrollment in forensics courses jumped, and it has remained high. By 2002, the effect was pronounced enough that juries were coming to expect greater forensic detail at trial and criminals were becoming (relatively speaking) more adept at covering their tracks.

Unfortunately, the unreality of televised forensics was also beginning to give people the wrong impression about what to expect from forensics. It's not typical for the same individual to photograph the scene, collect evidence, transport it to the lab, analyze it, capture the bad guy, interrogate him, and then testify at the trial. But this bit of dramatic license is not nearly as damaging as the simplification of the science. judge by the most comprehensive study on the reliability of forensic evidence to date, the error rate is more than 10% in five categories of analysis, including fiber, paint and body fluids. ...DNA and fingerprints are more reliable but still not foolproof....a 2005 study in the Journal of Criminal Law & Criminology suggests a fingerprint false-positive rate a bit below 1%, a widely read 2006 experiment shows an alarming 4% false-positive rate.

How can we preserve the usefulness of forensic evidence while protecting the public when it breaks down? The core problem with the forensic system is monopoly. Once evidence goes to one lab, it is rarely examined by any other. That needs to change. Each jurisdiction should include several competing labs. ...

This procedure may seem like a waste. But such checks would save taxpayer money. Extra tests are inexpensive compared to the cost of error, including the cost of incarcerating the wrongfully convicted....

Other reforms should include making labs independent of law enforcement and a requirement for blind testing. When crime labs are part of the police department, some forensic experts make mistakes out of an unconscious desire to help their "clients," the police and prosecution. Independence and blind testing prevent that.

That's forensics expert Roger Koppl writing in Forbes [Alex Tabarrok of MR did the work of selecting the quote].

Would the situation be improved if the lay public knew a bit more about the intricacies of arguing from uncertainty? What constitutes a reasonable doubt in a case that relies on several pieces of physical evidence each of which has a 10% error rate? Can CSI's techno-beats and hot forensics techs make statistics sexy?

1 comment:

Anonymous said...

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