The use of DNA statistics in criminal trials

In a number of recent cases in the UK, convictions have been quashed by the Court of Appeal on the grounds that the jury had been misdirected as to the factual significance of random occurrence statistics. The mathematical basis on which those statistics are calculated was reviewed and recent appeal cases involving DNA evidence in the UK and the US were examined. It was found that a widespread misconception exists regarding the random occurrence ratio and its relationship with probability of guilt. It is in fact impossible to relate the two with any degree of accuracy without consideration of social and demographic factors particular to a case as well as any non-DNA evidence obtained.