The statistical basis of DNA evidence presented to the court was incorrect in principle. It suffered from the ‘prosecutor’s fallacy’. The court described the nature of DNA evidence: ‘The process of DNA profiling starts with DNA being extracted from the crime stain and also from a sample taken from the suspect. In each case the DNA is cut into smaller lengths by specific enzymes. The fragments produced are sorted according to size by a process of electrophoresis. This involves placing the fragments in a gel and drawing them electromagnetically along a track through the gel. The fragments with smaller molecular weight travel further than the heavier ones. The pattern thus created is transferred from the gel onto a membrane. Radioactive DNA probes, taken from elsewhere, which bind with the sequences of most interest in the sample DNA are then applied. After the excess of the DNA probe is washed off, an X-ray film is placed over the membrane to record the band pattern. This produces an auto radiograph which can be photographed. When the crime stain DNA and the sample DNA from the suspect have been run in separate tracks through the gel, the resultant auto-radiographs can be compared. The two DNA profiles can then be said either to match or not.’
Judges:
Lord Taylor CJ
Citations:
Times 10-Jan-1994
Jurisdiction:
England and Wales
Cited by:
Cited – Regina v Clark CACD 2-Oct-2000
. .
Cited – Regina v Doheny, Adams CACD 31-Jul-1996
The court set out the procedure for the introduction of DNA evidence in criminal trials. In particular the court explained the ‘Prosecutor’s Fallacy’ when using statistical evidence. The significance of the DNA evidence will depend critically upon . .
Lists of cited by and citing cases may be incomplete.
Criminal Evidence
Updated: 25 October 2022; Ref: scu.86526
