Judgment date: 22 June 2011. Dasreef Pty Ltd v Hawchar  HCA 21. High Court of Australia1.
- Overruling the decision of the NSW Court of Appeal, the High Court found that expert evidence was inadmissible for the purpose for which it was used by the trial judge.
- The NSW Court of Appeal was wrong to conclude that the trial judge was entitled to take account of his experience as a member of a "specialist" court in determining the cause of injury.
Mr Nawaf Hawchar commenced proceedings in the Dust Diseases Tribunal of New South Wales against his employer, Dasreef Pty Ltd (Dasreef), alleging that his occupational exposure to dust containing silica caused his silicosis.
In support of his claim, Mr Hawchar sought to rely upon the expert opinion of Dr Kenneth Basden in order to establish what steps were available to Dasreef to minimise the risk of injury from the inhalation of dust containing silica. As part of his evidence, Dr Basden also commented on the likely concentrations of silica dust to which Mr Hawchar would have been exposed, suggesting that it would have been 500 or 1000 times greater than the permissible levels of exposure. However, Dr Basden sought to qualify his opinion as "only a ballpark to justify the reason I was recommending the protection factor... that was the purpose of it." Adopting Dr Basden's estimates, the trial judge proceeded to calculate the levels of dust containing silica to which Mr Hawchar was exposed.
The trial judge also professed to rely upon his experience from hearing evidence in previous matters as a judge of a "specialist tribunal" in concluding that Mr Hawchar's silicosis was caused by exposure to dust containing silica.
Court of Appeal Decision
Dasreef appealed to the NSW Court of Appeal against the whole of the orders made by Curtis J in the Dust Diseases Tribunal. Dasreef argued that the trial judge had erred in admitting evidence of Dr Basden as to the numerical level of respirable silica dust in Mr Hawchar's breathing zone. Dasreef also alleged that the trial judge had erred in relying on his experience as a judge of a specialist tribunal.
In relation to the admissibility of Dr Basden's evidence as to the levels of Mr Hawchar's exposure to dust containing silica and the manner in which the trial judge used that evidence, the Court of Appeal found that:
Whilst the Court of Appeal described Dr Basden's estimate as "contestable and inexact"3, it was open for Dasreef to contest the evidence by qualifying their own expert.
The Court of Appeal4 allowed the appeal in relation to certain questions of costs, remitting those questions to the Tribunal for reconsideration, but otherwise dismissed the appeal.
High Court Decision
French CJ, Gummow, Hayne, Crennan, Kiefel and Bell JJ delivered a joint judgment whilst Heydon J delivered a separate judgment, with a detailed analysis of the principles to be considered when assessing the admissibility of expert evidence.
The High Court examined s 79(1) of the Evidence Act 1995 stating that for expert evidence to be admissible, the witness must first have "specialised knowledge based on the person's training, study or experience" and that the expert opinion expressed must be "wholly or substantially based on that knowledge".
The admissibility of expert opinion evidence must be determined by the requirements of the Evidence Act 1995 and as enunciated in Makita (Australia) Pty Ltd v Sprowles5.
The High Court found that there was no evidence that Dr Basden's opinion regarding the extent of Mr Hawchar's exposure to dust containing silica was based on Dr Basden's training, study or experience. The estimate expressed by Dr Basden was nothing more than a "ballpark" figure and was not intended to be an assessment which could form the foundation for the type of calculation which was applied by the trial judge.
In terms of the issue of judicial notice, the High Court found that the trial judge had erred when he said that he was permitted to take his experience into account in determining what caused Mr Hawchar's silicosis.
Notwithstanding Dasreef being successful on both grounds of appeal, the High Court found that there was sufficient undisputed evidence for Dasreef to be held liable to Mr Hawchar in damages.
The High Court concluded the following:
This decision has not altered the landscape of admissibility of expert evidence as laid down in Makita (Australia) Pty Ltd v Sprowles7.
The decision is, however, a reminder that consideration should not only be given to the qualifications of a witness professing to give an expert opinion, but also the manner in which that evidence is ultimately used by the trial judge.
1. French CJ, Gummow, Hayne, Heydon, Crennan, Kiefel and Bell JJ
2. Dasreef Pty Limited v Hawchar  NSWCA 154 at 42
3. Dasreef Pty Limited v Hawchar  NSWCA 154 at 43
4. Allsop P, Basten and Campbell JJA
5.  NSWCA 305
6. at 10
7.  NSWCA 305
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