Natty Shafer Law

Utah lawyer for criminal and immigration cases

Tag Archives: forensic testimony


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Junk Science Continues to Plague Criminal Justice System

The criminal justice system is still suffering from decades of poor forensic evidence. One of those fields, microscopic hair comparison review, has been in the news lately. The FBI has been reviewing cases where their experts gave testimony about supposed hair matches. They found that in over 95 percent of the cases reviewed the FBI’s own forensic examiners overstated the forensic matches.

It is unfortunate that there has not been more of an outcry over this story. It is bad enough that innocent people have been sent to jail. There is no other way to describe this but as a tragedy. We know people have spent years, even decades, in jail for crimes they have not committed. It also means that law enforcement stopped looking for the person who actually committed these crimes. Perpetrators likely remain free, committing more crimes, because the law enforcement agency stopped investigating.

The problem with hair analysis is it is not scientific. It is subjective. When comparing two strands of hair, the identifiable characteristics of each strand are limited. Usually, what can really be determined by looking at a hair under a microscope is its color. That might, for example, narrow the field of suspects if the police think the perpetrator has red hair, but that strand of hair cannot definitely be said to come from any one person (unless there is DNA attached).

For decades FBI analysts were testifying in court that they could identify matches, sometimes going so far as to say they could positively identify them. Local forensic agencies followed the FBI’s lead. Countless people have been wrongly convicted, but the wheels of justice have been slow to reverse the wrongfully convicted.

By Nevit Dilmen - http://creativecommons.org/licenses/by-sa/3.0/. Licensed under CC-BY-SA-3.0 via Wikimedia Commons.


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Science and Forensics, Part 1: Introduction

The criminal justice system has a problem. No one knows just how reliable some types of forensic evidence are. These forensic fields were developed by crime investigators instead of by scientists. Not only haven’t they been proven to be reliable, there’s a question of whether or not they’re based on science at all. Some of them are better classified as superstition, but the criminal justice system has been slow to weed them out.

Bad forensic evidence usually makes its way into Utah courtrooms through expert testimony. Someone can testify about their credentials—frequently from spurious colleges or organizations—and then the court certifies them as an expert in a particular field. Under the Utah Rules of Evidence, judges are supposed to prevent experts from testifying about junk science. Utah Rule 702 governs expert testimony, and judges are required to make sure that the specialized knowledge that the expert purports to have is “reliable,” “based upon sufficient facts or data,” and has been “reliably applied to the facts.” Most judges do not have the expertise necessary, however, to determine if an expert’s testimony actually meets that criteria.

In a previous post, I argued that juries demanding that forensic evidence accompany eyewitness testimony has been a positive trend for criminal justice. I still believe that, but it’s also important that hard science support all forensic testimony.

The best forensics were developed independently from crime investigation and have other applications. DNA evidence is the gold standard for good forensic evidence. Everyone has DNA, it’s unique (even identical twins have a little variation), it’s quantifiable, and DNA tests can be replicated from one lab to another. Through CODIS (the Combined DNA Index System), the FBI keeps a large database of individuals’ DNA to help identify suspects in certain crimes. The one drawback is, unlike on television where it takes just a few minutes, it actually takes weeks to get the results.

Some forensic fields lack applications beyond crime investigation and don’t have independent verification. Those fields need to be subjected to the scientific process. That includes independent experimentation, peer review, and the ability to replicate conclusions. Most people are surprised when they learn that much of the forensic evidence that we were led to believe is scientific, has actually never been subjected to the scientific process, and no one has proved that they are reliable. In such fields, two different experts can come to completely different conclusions or their conclusions can be influenced by what they know about the crime they are investigating.