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How Good Is Forensic Evidence?

By Christopher Coble, Esq. on November 15, 2015 | Last updated on January 05, 2022

Part of the reason we gravitate to shows like "Dexter" and "CSI" is the problem-solving element -- we want to figure out whodunnit, hopefully before the show does. We also love these shows because they show off all the fancy technology and science behind crime solving -- it's like Sherlock Holmes came alive in the 21st century.

But did Holmes ever get it wrong? We are often so wowed by the "CSI effect" we fail to question if the science behind the gotcha evidence is sound. And to be fair, we're not scientists, so what position are we in to second-guess the experts? But more and more questions are being raised about real-world forensic evidence and the crime labs that process and interpret that evidence. So just how reliable is forensic evidence, anyway?

She Blinded Me With Science

The term forensic evidence refers to a wide array of evidence, everything from shoe and fingerprints to blood spatter and DNA sequences. And much of this science is sound. Comparing DNA samples in order to exclude suspects, for example, is based on widely accepted scientific principles. So as long as there are no problems with the quality of the sample, the chain of command, and the reporting of results, DNA science is good.

The problem comes with the human element. When people are asked to interpret evidence, the results are not as good. It turns out that even trained personnel make mistakes comparing fingerprints and bite marks. And judges are people, too, and may have trouble deciding which forensic evidence is legitimate and which is a sham.

And Failed Me in Biology

As Slate reported last month, there is an ongoing scandal in the Massachusetts state drug analysis unit. One chemist is serving a three-year prison sentence for falsifying the results of drug tests while another was addicted to drugs, stole from the lab, and performed analyses while under the influence. Between the two scandals, falsified or faulty drug tests could have affected 40,000 criminal cases.

The science behind testing blood, urine, and hair for traces of drugs is some of the most reliable in the forensic community. The problem is that some of the analysts don't meet that same bar. If you've been charged or convicted based on forensic evidence make sure you talk to an experienced criminal defense attorney about your case.

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