SYDNEY // New research has revealed that Australian juries are often overwhelmed by DNA evidence presented in criminal cases and rarely question its reliability. The Australian Institute of Criminology also found that the less jurors understood about the complexities of genetic science, the more likely they were to find a defendant guilty because of a naive acceptance of its validity.
"One of the problems is that it seems jurors have some difficulty understanding the significance of the evidence that is introduced by forensic scientists. They seem to have been blinded by science or seem to be susceptible to what others have called the 'white coat effect'. They are not scrutinising the content of the evidence adequately to give it appropriate weight," said Jane Goodman-Delahunty, a professor in the Australian Graduate School of Policing at Charles Sturt University, who carried out the research.
"This can mean that the conviction rate is very high in cases where oftentimes very circumstantial DNA evidence is introduced and that is the only link between the defendant and the crime scene." Four hundred Australians took part in the study and participated in a mock murder trial to establish how the judges responded to the DNA evidence. Those with a poor grasp of the methodology were almost twice as likely to reach a guilty verdict than those with a greater awareness of the process.
"We were able to show that along with the increase in DNA knowledge, the conviction rate decreased significantly as well. That was a demonstration that the more people understood in terms of the content of the science the less likely they were to simply accept without criticism the expert evidence," Ms Goodman-Delahunty said. Some lawyers believe that the popularity of television dramas such as CSI: Crime Scene Investigation and Law and Order can distort jurors' views on the dependability of genetic samples.
Michael McNamara, a solicitor in Melbourne, said neatly packaged stories that simplify complicated procedures could well persuade viewers to believe that DNA testing is an infallible tool. "Unfortunately a lot of television has even the grandest murder fixed in an hour and they see the scientist say 'this is how we prove it and this is what we do'. It is all believable and the guy in the white coat is the expert and perhaps dazzles them," Mr McNamara explained.
Recent questions about the accuracy of genetic material used as evidence has forced authorities in the country's most populous states, New South Wales and Victoria, to investigate possible shortcomings in the way that new equipment interprets forensic data. "There are a couple places where human error can occur: when it is collected and when it is being tested. In Victoria, we've got real problems with how robust the DNA evidence is in the first place. They closed the lab here for a while. We have our concerns that the methodology is perhaps still wrong," Mr McNamara said.
Such concerns have raised the likelihood that innocent men and women have been locked up for crimes they did not commit. In December, Farah Jama, 22, a Somali migrant, was freed after 15 months in prison when a rape conviction was overturned because a DNA sample had somehow been contaminated in a laboratory. "I feel really depressed and cannot imagine what happened," Mr Jama said when he was released outside the Victorian Court of Appeal. He had insisted that he had been reciting the Quran to his seriously ill father at their Melbourne home when the alleged assault took place.
Loane Skene, a law professor at the University of Melbourne, said that although the underlying science was essentially sound, there were clearly problems with DNA testing. "The positives do outweigh the negatives, but I do think we have to be cautious in the way that we use DNA evidence," Mr Skene said. "It doesn't necessarily prove that a person committed a crime. Somebody else could have put the DNA there, for example. One of the concerns is the accuracy of tests based on a very small amount of DNA from a crime scene and if it has been contaminated in the course of being collected that obviously undermines the significance of the DNA."
The criminology institute has suggested that jurors be given a short scientific multimedia tutorial before any trial at which genetic evidence will be used, a proposal that has the support of the Law Society of New South Wales. email@example.com