Enhancing fairness in DNA jury trials

Foreword | Controversies over how the law should regulate the presentation of expert testimony on DNA forensic science were explored in an experimental study comparing traditional verbal with audiovisual modes of delivery. Pre-trial DNA knowledge, as assessed in 3,611 jury-eligible Australians, was limited. From this group, 470 citizens watched a simulated homicide trial containing a cognitively-sequenced generic tutorial on DNA profiling evidence. The expert tutorial significantly improved DNA knowledge, irrespective of the mode of presentation. Given clear and well-sequenced complex information, lay jurors dealt competently with it. Only jurors with little knowledge of DNA who were exposed to verbally presented evidence deferred to the expert's views. The multimedia tutorial effectively improved the decision-making of people whose comprehension of the scientific evidence was lowest, bringing their verdicts in line with those whose understanding of the evidence was most accurate. Enhanced DNA knowledge increased scepticism about experts and reduced convictions. These results will aid courts and policymakers in adopting procedures to enhance justice in criminal cases in which DNA is introduced. Adam Tomison Director Use of DNA evidence in Australian courts has increased exponentially since 1989 (Easteal & Easteal 1990; Walsh et al. 2004). After 20 years, DNA technology is well-tested and is no longer the subject of defence challenges (Haesler 2008). Increasingly, a single forensic expert guides the jury through the DNA evidence; in five out of six DNA cases studied in New South Wales, this was the model (Findlay 2008). The presence of DNA evidence predicts convictions. Archival research revealed that juries were 23 times more likely to vote guilty in homicide cases and 33 times more likely to vote guilty in sexual assault cases when DNA evidence was admitted (Briody 2004). Concern has arisen that the safety of these verdicts may be compromised by widespread misconceptions about the infallibility of DNA evidence (Gans & Urbas 2002) by jurors who are Overawed by the scientific garb in which the evidence is presented and attach greater weight to it than it is capable of bearing' (R ? Duke 1979 22 SASSR 46 per King CJ: 48). Field studies, interviews with actual jurors and jury simulations confirm that individual jurors struggle to understand and apply the statistical information conveyed by forensic experts about the likelihood that the DNA match occurred randomly, by chance alone (Findlay & Grix 2003; Lieberman et al. 2008; Schklar & Diamond 1999; Wheate 2006). The problem with misunderstood evidence is that it may compromise justice. Post-trial interviews of jurors who served on six criminal trials in New South Wales disclosed that jurors who admitted difficulty understanding DNA expert evidence nevertheless proceeded to convict (Findlay 2008). To minimise biases, investigation of methods to facilitate juror understanding of the probative value of DNA evidence was identified as a crucial area for empirical research (National Research Council 1996). Attention first focused on a traditional legal safeguard- jury directions. In Australia, the judiciary were advised to 'develop a model jury direction for use where DNA evidence has been admitted in criminal proceedings' to aid judges and juries in evaluating DNA evidence (ALRC 2003: Ree 44-2). However, one controlled experiment testing the Australian Law Reform Commission's model instruction showed it was ineffective (Dartnall & Goodman-Delahunty 2006). Jury deliberation has also proved inadequate (Findlay 2008; Wheate 2006). Jurors' educational levels were more substantial contributors to comprehension than deliberation (Dann, Hans & Kaye 2007). Recently, attention has shifted to features of the expert evidence (Bornstein 2004), to reduce misplaced reliance by jurors on pre-existing beliefs about DNA profiling and to enhance jury comprehension (Edmond & Mercer 1999). …