Expert witnesses to play vital role in Bourke Street Driver’s fate

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This month a jury has been discharged after failing to agree whether Dimitrous Gargasolous, who is accuse of driving into a crowd of people in Melbourne’s Bourke Street Mall in January last year, is mentally fit to stand trial. The jury began its deliberations on a Monday afternoon but, after a special hearing which saw three mental health experts give evidence, the jury were still unable to decide [1].

Even though in Australia there is no formal process for psychologists to be eligible to provide their expert opinion in court, it has been found that jurors tend to take expert psychological opinions very seriously, with expert opinions being “welcomed and valued”.[2] Highlighting the importance of utilising expert witnesses with proven court experience, juries perceive expert witnesses who are confident and can maintain eye contact as more credible,[3] suggesting that a jury’s decision may have a lot to do with the performance of an expert, as well as the substance of their evidence.

The lack of a formal process for psychologists to act as expert witnesses may be detrimental to court proceedings, as psychologists and other experts do not always provide sufficient evidence by virtue of their medical qualifications alone.[4] A survey taken by judges shows that there were frequently numerous issues with expert evidence. Common issues include poor examination performance and a failure to provide bases for their opinions.[5] This suggests that some sort of compulsory expert witness training would be of enormous benefit for experts desiring to act as expert witnesses, and also to the efficiency of court proceedings. Were such compulsory training implemented in Australia, it would that ensure all expert witnesses had a certain level of competency and would know what was required of them in a court situation.

During the trial, two psychiatrists gave evidence concluding Gargasoulas was unfit to stand trial because they did not believe he could enter a plea, nor was able to properly instruct his lawyers and understand the effect of evidence against him.

Psychiatrist Andrew Carroll, who was in fact engaged by the prosecution agreed Mr Gargasoulas was unfit to stand trial as he was affected by a “messianic delusional belief the he is the saviour”.

Dr Carroll said Mr Gargasoulas was aware of the legal recourse available to him but that his primary concern was gaining a public platform to espouse his ideas.

But another mental health expert, psychologist Michael Daffern, argued Gargasoulas was indeed fit to stand trial. Professor Daffern told the jury that, based on his assessment of the accused, he thought Gargasoulas was able to put aside his delusions in order to consider his legal options.

The decision may well be determined in part by the strength of the experts’ reasoning and performance in court, illustrating the important role that an expert witness’s competence plays in the Australian criminal court system.


[1] ABC News at <>

[2] Suzanne Blackwell & Fred Seymour ‘Expert Evidence and

Jurors’ Views on Expert Witnesses’ (2015) Psychiatry, Psychology and Law 22.5. 673, 674.

[3] Ibid 678.

[4] Elena Gianvanni & Stefanie J. Sharman ‘Psychologists as Expert Witnesses in Australian Courtrooms’ (2015) Psychiatry, Psychology and Law 22.6. 920, 923

[5] Ibid 924.

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