If you are a fan of crime shows like CSI, you are already familiar with the power forensic evidence has in determining the guilt or innocence of someone charged with a crime. Although television shows often portray such evidence as unimpeachable and always reliable, in real life, this is sometimes not the case, as a recent FBI review of criminal cases involving hair comparison evidence demonstrated. Hair comparison evidence is one of the most common types of evidence used in criminal trials. It is used primarily to tie (or eliminate) a suspect to a crime scene or crime victim.
As of April of this year, the FBI reviewed 342 cases that involved hair comparison evidence. This type of evidence was used in the prosecution of suspects in 342 cases. The review determined that in 95 percent of those cases, including 32 death penalty cases, the reliability of this type of evidence was overstated at trial, potentially leading to the wrongful convictions of an unknown number of suspects.
According to the Innocence Project, the overstating of the reliability of hair comparison evidence is only the tip of the iceberg. The organization reports that other types of forensic evidence whose reliability and accuracy have never been scientifically tested or conclusively validated as reliable are routinely used in criminal trials. This includes tests such as shoe prints, bite mark or voice comparisons, and firearm tool marks. Since this unreliable evidence is used in criminal cases involving everything from murder and assault to sex crimes, it may result in many facing wrongful charges or convictions for crimes they did not commit.
Problems with forensic evidence are broader
Sadly, the use of unreliable evidence is not the only cloud hanging over forensic evidence. Sometimes, misconduct or mistakes on the part of analysts performing forensic tests can have the same results. As analysts and scientists are only human, sometimes they make innocent mistakes because of inadequate training, lack of resources or simple human error. In other less frequent cases, certain analysts or scientists intentionally fabricate results or fail to report findings that may hurt the prosecution's case. Although these cases are rare, a single analyst committing this type of misconduct can taint thousands of cases.
As an example, in one famous case, a Massachusetts crime lab chemist admitted in 2012 to identifying substances by "eyeballing" them (i.e. judging composition by their appearances), rather than running a chemical test to learn of the chemical makeup of the substances. Unfortunately, by the time the misconduct was discovered, the chemist had "tested" over 60,000 samples. As a result of the misconduct, many wrongfully convicted of drug charges based on the faulty evidence were released.
If accused, seek legal help
If you are accused of a crime, based on the results of forensic tests, do not make the mistake of assuming that your guilt has been conclusively proven because of the scientific or technical nature of this type of evidence. It is important, however, for you to have competent legal representation familiar with forensic evidence and its limitations. An experienced criminal defense attorney can evaluate the evidence against you to determine weaknesses and inconsistencies, and work to obtain the most favorable outcome possible for you.