Introduction

44.1 DNA evidence may be used in criminal proceedings by either the prosecution or the defence. For example, the prosecution may seek to introduce DNA evidence of a match between a bodily sample found at a crime scene (or on or in the victim), and a sample taken from the defendant, to suggest the likelihood that the defendant committed the offence, or was at least present at the crime scene. The prosecution gives weight to evidence of such a match by offering statistical evidence of the relative probability that the sample found at the crime scene might have come from any person other than the defendant. Alternatively, the defence may seek to rely on DNA evidence to establish that the crime scene sample does not belong to the defendant or otherwise to dispute the prosecution’s evidence. This Chapter considers the particular ethical and privacy issues arising in relation to the use of DNA evidence in criminal proceedings.

44.2 A number of early Australian cases supported the exclusion of DNA evidence on the basis that the probative value of the evidence was, in the circumstances, outweighed by its prejudicial tendencies. More recently, courts have taken the view that conflicting expert opinions regarding the evidence are a factual matter for the jury to determine, subject to appropriate judicial direction.^[1] The issues usually raised on appeal concern whether the trial judge properly exercised his or her discretion to admit the DNA evidence; whether the evidence was properly presented and explained by a qualified expert witness; and whether the trial judge gave the proper directions to the jury on the application of the evidence.^[2]