Research: Forensic evidence in criminal cases needs closer scrutiny

Research reveals that some widely used forensic techniques have not been scientifically proven reliable and are often portrayed misleadingly during trial.

To many people in Pennsylvania, forensic evidence may seem like one of the most reliable forms of evidence that may be used to support criminal charges. This evidence is widely represented as accurate and objective, both in media portrayals of crime scene investigation and in the testimony that forensic analysts give at trial. Forensic evidence also can be decisive in high-stakes cases, including ones that involve allegations of sexual offenses, assault and more. Troublingly, though, research increasingly shows that this type of evidence is not infallible.

The Innocence Project has examined more than 300 cases in which wrongfully convicted individuals in the U.S. were exonerated on the basis of DNA evidence. Shockingly, issues with forensic evidence were the second most common contributing factor to these convictions. Overall, unreliable forensic evidence played a role in over four out of 10 wrongful convictions.

Questionable techniques

Forensic evidence can be misleading or unreliable for several reasons, including innocent errors on the part of analysts, deliberate misconduct and the use of scientifically unvalidated techniques. In 2016, a report from the President's Council of Advisors on Science and Technology revealed the seriousness of the latter issue. According to The Washington Post, after reviewing several widely used "pattern-matching" forensic techniques, a panel of scientists concluded that there was no empirical evidence to support the reliability of the following techniques:

· Hair microscopy analysis

· Firearm and tool mark examination

· Shoe tread comparison

· Bite-mark analysis

Per the Pittsburgh Post-Gazette, the report suggests that some of these techniques, such as firearm and tool mark examination, are based on sound principles. With further research and technological improvements, these methods may eventually provide reliable evidence. However, other techniques, such as bite-mark analysis, are unlikely to ever offer accurate insights.

Overstated accuracy

Alarmingly, even when forensic techniques lack scientific backing, the resulting evidence is often admitted in trial and presented to juries as highly reliable. In one chilling example, the FBI reviewed more than 250 cases in which its analysts provided testimony regarding hair microscopy analysis. In over 98 percent of those cases - including 35 death penalty cases - analysts overstated the reliability of this evidence, potentially contributing to wrongful convictions or guilty pleas by innocent individuals.

Challenging forensic evidence

Sadly, statistics suggest that questionable forensic evidence may harm many people who have been charged with misdemeanors or felonies here in Pennsylvania. According to data from the National Registry of Exonerations, 14 out of 64 wrongful convictions that have occurred in the state involved misleading or false forensic evidence. Such evidence may contribute to even more wrongful convictions that have not yet been uncovered.

These findings are just one reason that it is critical for anyone facing criminal charges in Pennsylvania to seek legal help. An attorney may be able to craft a defense strategy based on any weaknesses in the case against a person, including issues with forensic evidence, and ensure that these issues are properly considered at each stage of the criminal justice process.