How DNA Evidence Went From Airtight to Error-Prone

Blind faith in any technology can be dangerous -- especially when it comes to areas of forensic science such as DNA fingerprinting. For example, if police have “DNA evidence” against a suspect, most juries will assume that’s proof of guilt. But while the technology for analyzing DNA has become vastly more sensitive since it was first introduced in courts in the 1990s, crime labs are working with ever more minute traces -- sometimes just a few molecules -- and drawing inconsistent or erroneous conclusions from them. In fact, there’s good reason to believe DNA evidence has sent people to prison for crimes they didn’t commit. Read more here.

PCAST Report Final Issued

Report on Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods

On September 20, 2016, PCAST released a Report to the President on Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison


DNA Evidence Is Not Infallible

Earlier this month, the Texas Forensic Science Commission raised concerns about the accuracy of the statistical interpretation of DNA evidence, and it is now checking whether convictions going back more than a decade are safe.

Despite how it is often portrayed, in the media and in courts, the forensic science of DNA is far from infallible. Particularly concerning is that police and prosecutors now frequently talk of 'touch DNA' — genetic profiles of suspects and offenders that have been generated in a laboratory from just a handful of skin cells left behind in a fingerprint.

Research done by me and others at the University of Indianapolis in Indiana has highlighted how unreliable this kind of evidence can be. We have found that it is relatively straightforward for an innocent person's DNA to be inadvertently transferred to surfaces that he or she has never come into contact with. This could place people at crime scenes that they had never visited or link them to weapons they had never handled.

Such transfer could also dilute the statistics generated from DNA evidence, and thereby render strong genetic evidence almost insignificant. (The statistics issue is reportedly the focus of the Texas investigation.)

read more at: http://www.nature.com/news/forensic-dna-evidence-is-not-infallible-1.18654?


DNA Mixture Interpretation and the Law

DNA mixtures

Recent developments in the Texas criminal justice system may point towards the necessity of, once again, looking back at convictions because of DNA. This time however, the issue is not the certainty which DNA can provide a jury that other evidence cannot. Rather, the issue centers around the recent changes in interpretation guidelines for mixtures, and the extent to which convictions based on the previous methods of calculating results were misleading to juries. This issue may be much more problematic for criminal justice systems to deal with then the first time DNA gave us reason to look backwards. But deal with it they must.

Read more  here