Download a PDF of Chapter 5 – Trial (12 pages)
Since this report was published, there have been a number of developments in this area of law. The information below applies to the time at which the report was published. For information aboutchanges since 2007 please see:
The forensic use of bioinformation – 2010 update (PDF 31 KB)
DNA and fingerprints can only assist in a prosecution when the science is robust, and is interpreted and represented accurately. In addition, how and when the DNA sample or fingerprint came to be at a crime scene would always need to be verified with further evidence. Therefore, care needs to be taken over how bioinformation evidence is used in court.
Fingerprints are analysed by experts who decide whether or not, in their opinion, there is a true match between the crime scene mark and the accused person’s print.
When presenting their opinion regarding a fingerprint match, fingerprint experts should make it clear that their conclusion is always one of expert judgment, and not a matter of absolute certainty.
DNA evidence is very influential in court, but it is accompanied by complicated statistical information that can be difficult for non-scientists to understand. For example, a profile that might by chance occur in one in a million people in the UK may be mistaken to mean that the chance of the defendant being innocent is one in a million.
Legal professionals should acquire a minimum understanding of statistics with regard to DNA evidence. Information should also be made available to jury members about the capabilities and limitations of DNA evidence.