It seems easy on television. A crime is committed, crime scene techs come in and prove who did or did not commit the crime based on a stray hair, or a tennis shoe print. For a time it seemed to be that concrete in the real world too. Bite marks, hair identification, footwear analysis all seem to offer irrefutable evidence when it has been used in court and presented by forensic specialists. The problem is, there often is little if any scientific validation of the veracity of these kinds-and other kinds-of evidence.
For years, and in some cases for decades, some tests that require forensic feature-comparison methods have been considered almost infallible. In reality, they are actually fallible, and perhaps very unreliable. The FBI and the Innocence Project conducted a joint study to examine hair evidence that had been used in felony trials. They found flaws in 95% of the testimony given based on hair used for the trial.
Just as frustrating is the fact that DNA testing has proved that a great number of bite-mark evidence is wrong even though presented forensically at trial. Faulty forensic evidence has also been found in nearly half of all legal cases which led to the exoneration of the convicted parted after DNA testing was used. Forensic mistakes are leading to people being convicted for crimes they did not commit.
An important result of this study was that respected scientists conducted the evaluation and determined that forensic methods are not reliable enough to put an accused’s freedom in jeopardy. It was found that many techniques used to help determine a person’s innocence or guilt could not meet scientific levels of accuracy. If the study about the accuracy of forensics is correct, the science should not be used in the courtroom.
A frustration is that judges rely on forensic testimony to ensure evidence is fairly presented. Techniques that have been used for years and decades have now had their scientific validity brought into question. Although some judges have tried to offer limits, presented to juries verbally, on how some forensic evidence is presented, it is unclear as to how this helps juries understand what is to be trusted explicitly, and what may be no better than junk science.
For now it will be the role of the adversarial system and vigorous cross examination that will have to be relied upon to present the potential unreliability of evidence. At least until the legal system determines a way to sort junk science from reliable forensic science, it appears criminal defense attorneys will have to continue to provide clarity for the courts on behalf of their clients.