Why Flawed Evidence Makes It To Trial

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The long and complicated trial and acquittal of Casey Anthony in the murder of her 2-year-old daughter has raised a lot of questions.

For instance, during the trial, the prosecution claimed that Anthony had searched the term "chloroform" 84 times on her computer.

But it turns out, the software was wrong, and there was only a single search for chloroform.

The software developer said he even told prosecutors about the initial error, but the questionable evidence was never retracted. How is it that such flawed information can make its way into a trial?

Jonathan Koehler, Beatrice Kuhn professor of law at Northwestern University, told Here & Now's Robin Young, "Forensic errors are nothing new."

In fact, he said forensic experts don't have to be licensed and not all of the laboratories they work in are even accredited.

Koehler is calling for a system to track and report the errors of forensic scientists.

“We need there to be a mechanism for testing experts on a regular basis to identify the error rates in the various forensic disciplines," Koehler said.

Once the error rates are know, Koehler says they should be reported to juries, so that they can take that information into account when weighing the evidence.


  • Jonathan Koehler, the Beatrice Kuhn Professor of Law at Northwestern University

This segment aired on August 4, 2011.


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