Juries listen carefully when forensic scientists give evidence, and Florida prosecutors know this. Scientific evidence has long been used to prove that an individual visited a location, touched an object or left a drop of blood behind, and DNA testing can link tissue samples to individuals with 99.9% accuracy. However, not all forensic evidence is rooted in established science. Bloodstain-pattern analysis and 911 call analysis are two areas of forensic science that became extremely popular with prosecutors because the evidence they presented was compelling and easy for juries to understand. Bloodstain-pattern analysis and 911 call analysis are now considered junk science by most experts.
911 call analysis
The retired deputy police chief who developed 911 call analysis based on his 2006 master’s thesis had no scientific credentials and never took part in a homicide investigation. That did not stop the FBI from embracing his work and promoting it around the country. It was not long before detectives in American cities were analyzing voice recordings and looking for tipoffs like “guilty pauses,” and then prosecutors presented this evidence in court. The approach is not based on sound science or peer-reviewed research, and five studies have failed to find any evidence that it works. The FBI now cautions against using 911 call analysis as it may increase bias, and criminal defense attorneys would likely object to this kind of evidence being used in court.
Bloodstain-pattern analysis has been used in criminal trials in the United States since the 1970s. The analysis of blood patterns is based on the work of a renowned criminologist, but the technique fell out of favor with the scientific community when the National Academy of Sciences condemned it in a watershed 2009 report. Since the publication of that report, convictions based on this junk science have been overturned in several parts of the country.
Junk science is admitted as evidence when judges mistakenly believe that it is credible and reliable. Judges are not scientists, and the experts they hear from when they make these decisions work for either the prosecution or the defense. Before ruling on these matters, judges should consult with independent and impartial experts.