When a new forensic technology is developed, the scientific basis for the technology and its likely effect on the jury are scrutinized. Rightfully so, we are alarmed by the risk of prematurely applied science sending an innocent person to prison, and we are careful to prevent these mistakes. When it comes to admitting invalid evidence, preventing a mistake is easier than correcting one.

Unfortunately, many mistakes may have already been made. A recent Hastings Law Review article, “‘Good’ Science Gone Bad: How the Criminal Justice System Can Redress the Impact of Flawed Forensics” argues that many people currently in prison were convicted based on forensic evidence that is no longer considered scientifically valid. Comparative bullet lead analysis, fingerprints(!), and microscopic hair examination are among the techniques authors Jessica Gabel and Margaret Wilkinson criticize.

Post-conviction DNA analysis has exonerated many people who were originally convicted based on these forensic techniques and called their validity into question. According to the article, of the first 200 DNA exoneration cases, 113 involved introduction of faulty forensic evidence. Nearly 22% of those 200 people had been wrongly convicted largely on the strength of hair follicles found at the crime scenes. The authors propose legislation to create procedures for obtaining post-conviction discovery and an evidentiary hearing to challenge scientific evidence that has been shown to be unreliable after conviction.

We work hard to prevent invalid forensic evidence from being admitted because we know the consequences will be devastating. It makes sense we should work just as hard to correct our mistakes once those consequences have already been realized.

Jessica Gabel and Margaret Wilkinson, Good Science Gone Bad: How the Criminal Justice System Can Redress the Impact of Flawed Forensics, Hastings L.J. (May 2008).

– Kelly Lowenberg