Australian Institute of Criminology

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DNA identification in the criminal justice system

Media Release

22 May 2002

DNA (Deoxyribonucleic acid) evidence has been admissible in Australian courts since 1989 under some basic guidelines established within case law. However, expert opinion on the statistical analysis of DNA match likelihoods using general population genetic databases is particularly contentious, and may be difficult for juries to understand.

A paper released today by the Australian Institute of Criminology examines the science of DNA identification and its use during criminal investigations and in criminal proceedings.

A common use of DNA identification in criminal investigations is obtaining crime scene samples to construct a DNA profile for comparison with a suspect's profile or against a database of known offenders.

A 'match' of DNA profiles will justify further investigation of the suspect's involvement in the crime, while a 'non-match' will generally prompt alternative lines of inquiry and may, in the right circumstances, conclusively exclude the suspect. However, all matches must be treated with caution to eliminate alternative hypotheses of coincidence, kinship or sample contamination.

"This paper describes the main benefits and costs of the increasing role of DNA identification in the criminal justice system", said Dr Adam Graycar, AIC Director. "The major benefit obtained from DNA-based investigations is the establishment of a link between suspect and crime that leads to a conviction and punishment of the offender. Other benefits may include providing an efficient alternative to traditional means of investigation; deterring further criminal activity by those already on a database; and providing a means for reviewing convictions through appeals and other forms of post-conviction review such as 'innocence panels'".

Costs may involve increased use of DNA techniques to enhance surveillance at the expense of privacy and civil liberties, and rights against self-incrimination.