Unvalidated or Improper Forensic Science
Unvalidated or improper forensic science is a leading cause of wrongful conviction in the United States.
Many techniques still in use today -- such as hair microscopy, bite mark comparisons, firearm testing or tool mark analysis – have never been subjected to rigorous scientific evaluation. Other methods – such as serology (commonly known as blood typing) – have been properly validated but are sometimes improperly conducted or inaccurately conveyed in trial testimony. In some cases, forensic analysts have fabricated results or engaged in other misconduct.
In approximately 50% of DNA exonerations, unvalidated or improper forensic science contributed to the wrongful conviction. But, while DNA exonerations are a window into the effect of unvalidated or improper forensic science contributing to wrongful convictions, DNA does not solve the problem. Experts estimate that only 5-10% of all criminal cases involve biological evidence that could be subjected to DNA testing. In the other 90-95% of crimes, DNA testing is not an option – so the criminal justice system relies on other kinds of evidence, including forensic disciplines that may not be scientifically sound or properly conducted.
The Absence of Scientific Standards
As outlined in the National Academy of Sciences report, Strengthening Forensic Science in the United States: A Path Forward, many forensic disciplines have evolved primarily through their use in individual cases and have not been scientifically validated or standardized.
As a result, forensic analysts sometimes testify in cases without a proper scientific basis for their findings. Testimony about more dubious forensic disciplines, such as efforts to match a defendant’s teeth to marks on a victim or attempts to compare a defendant’s voice to a voicemail recording, are cloaked in science but lack even the most basic scientific standards. Even within forensic disciplines that are more firmly grounded in science, evidence is often made to sound more precise than it should. For example, analysts will testify that hairs from a crime scene “match” or “are consistent with” defendants’ hair – but because scientific research on validity and reliability of hair analysis is lacking, they have no way of knowing how rare these similarities are, so there is no way to know how meaningful this evidence is.
Forensic Misconduct
The vast majority of forensic employees are hardworking, ethical and responsible. They use the best scientific techniques available to deliver objective, solid information – regardless of whether the science favors the defendant, supports the prosecution or is inconclusive.
In many cases, the science – rather than the scientist – is inadequate. In other cases, forensic analysts make mistakes that could result from lack of training, poor support or insufficient resources to meet an ever-growing demand. But in some cases, forensic analysts have engaged in misconduct. While these “bad apples” don’t reflect the entire forensic field, one fraudulent forensic analyst can taint countless cases. For example, in some wrongful convictions later overturned with DNA testing, forensic analysts fabricated test results, reported results when no tests were conducted or concealed parts of test results that were favorable to defendants. In virtually all of these cases, analysts had engaged in misconduct that led to multiple separate wrongful convictions, sometimes in multiple states.
A Plan for Reform
Unvalidated and improper forensic science continues to play a role in convictions across the country, and the National Academy of Sciences report calls strongly for reform to help identify perpetrators of crimes and protect the innocent from wrongful convictions.
Learn more about the Just Science Coalition’s plan for reform here.