1 August 2011

Is the expert evidence admissible or not?

A new leading case on expert evidence.
Australia Litigation, Mediation & Arbitration
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Dasreef Pty Limited v Hawchar [2011] HCA 21


This case is now the leading authority on admissibility of expert evidence. Additionally, the High Court of Australia considered the proper trial procedure when ruling on objections to admissibility of evidence, and the extent to which it is legitimate for a judge of a specialist court to draw on experience when interpreting (or 'supplementing') expert evidence to make factual findings. This article considers the admissibility of expert evidence point. Moray & Agnew acted for the appellant, Dasreef.


Mr Hawchar undertook work for Dasreef from 1999 to 2005 initially as a labourer and then as a stonemason. He had worked for a family stonemasonry business in Lebanon before immigrating to Australia and had undertaken some 'private' stonemasonry work between 2002 to 2005. Most of the sandstone used by Dasreef was pre-cut to size by the supplier or cut using water dampened tools. Some cutting and shaping work was undertaken by Mr Hawchar using a non-water dampened grinder. The cutting work generated silica dust. Mr Hawchar alleged that, despite using a mask, he inhaled sufficient quantity of dust to be causative of silicosis and systemic scleroderma.

In October 2007, Mr Hawchar commenced proceedings in the Dust Diseases Tribunal of New South Wales ('the Tribunal'). He alleged that Dasreef was negligent and in breach of statutory duty by exposing him to excessive silica dust. Dasreef argued that in order to succeed it was necessary for the plaintiff to establish that the levels of exposure exceeded the permissible standard. The plaintiff relied on the opinion of Dr Basden, a chartered chemist, chartered professional engineer and retired senior lecturer in the school of Chemical Engineering and Industrial Chemistry at the University of New South Wales. Dasreef objected to the tender of Dr Basden's evidence on the basis that it did not satisfy s79(1) of the Evidence Act 1995 (NSW) ('the Evidence Act').

Dr Basden's evidence

Dr Basden had experience in the fields of aerosol technology in general, and the incidence of some types of fugitive dust in workplace and mining environments. Dr Basden did not have experience in quantification of silica dust levels experienced by stonemasons. He had not ever measured silica dust concentrations arising from relevant cutting work in the course of his professional life, nor had he undertaken research or study of the incidence of respirable silica dust following the cutting of sandstone with a grinder.

At best, Dasreef submitted that Dr Basden's qualifications permitted him to express an expert view on the quantification of inhalation through the mask if he had been given assumptions as to the level of exposure in the breathing zone. In that event it would have been necessary for Mr Hawchar to prove the assumptions by another expert qualified in that field or by undertaking testing of analogous cutting tasks.

Dr Basden purported to estimate the amount of respirable silica dust exposure which Mr Hawchar inhaled whilst working for Dasreef to have been 1000s fold higher than the applicable standard. The statement was not supported by any calculations of exposure nor references to testing of analogous dust exposures available in literature nor from testing undertaken by Dr Basden. Dasreef submitted the estimate amounted to a guess which was inadmissible.

Admissibility argument

The evidence of an 'expert' is a statement of opinion as to a fact. The Court is interested in evidence 'of' facts rather that evidence of 'interpretation' of facts and thus evidence of 'opinions' is usually inadmissible. The 'opinion rule' contained in s76(1) of the Evidence Act provides that:

'[e]vidence of an opinion is not admissible to prove the existence of a fact about the existence of which the opinion was expressed'

However, an exception to the inadmissibility of opinion evidence arises if the evidence is of an expert character. Section 79(1) of the Evidence Act provides that:

'[i]f a person has specialised knowledge based on the person's training, study or experience, the opinion rule does not apply to evidence of an opinion of that person that is wholly or substantially based on that knowledge'.

Admissibility was considered by the NSW Court of Appeal in 2001 in another Moray & Agnew case, Makita v Sprowles. Heydon JA (as he then was) wrote the leading judgment. The Court of Appeal held that in order to satisfy s79 it was necessary for the opinion to:

  • Be of an expert character
  • Be given by a person who by training, study and / or experience has expertise as to the specific subject matter of the opinion given
  • Provides the opinion in a written form providing sufficient description of the workings and references on which the opinion is based to enable it to be considered by the opponent.

Subsequent to Makita, decisions in the Federal Court (which is subject to relevantly identical legislation) criticised the 'Makita calculus' by saying it was too strict, particularly as to the degree of connection required between the expert's experience and the opinion. Those cases held that the opinion evidence ought to be admitted but the criteria identified by Heyden JA should be considered as to the weight that should be given to the evidence.

At trial and before the Court of Appeal Dasreef argued that the opinion was inadmissible because:

  • Dr Basden was not qualified in that his expertise did not extend to the particular opinion relevant to the case – that being the quantity of respirable dust created by the cutting of sandstone with a grinder
  • It was not possible to decipher the actual opinion being given from the report and or evidence
  • The opinion was not supported by reasoning. Mr Hawchar argued that the opinion was admissible and the issues raised by Dasreef went only to the weight that should be attributed to the evidence.

Mr Hawchar argued that the opinion was admissible and the issues raised by Dasreef went only to the weight that should be attributed to the evidence.

The Trial Judge accepted the opinion into evidence. That decision was upheld by the Court of Appeal which broadly construed the requirement that the opinion be based on the witnesses specialised knowledge. It held, consistent with the decisions of the Federal Court, that it was not necessary for the expertise to be specific to the opinion and that the Makita criteria in this case went to weight.

Dasreef was granted special leave to appeal to the High Court of Australia.

High Court of Australia

The High Court (in a joint judgment of French CJ, Gummow, Hayne, Crennan, Kiefel and Bell JJ and, in a separate judgment, Heydon J) unanimously upheld Dasreef's appeal on the test to be applied when assessing the admissibility of expert evidence.

The Court held that to be admissible the opinion must satisfy three criteria. First, the opinion must be on a subject matter that is expert in nature; secondly, the expert witness must have 'specialised knowledge based on the person's training, study or experience' specific to the opinion required; and thirdly, the opinion must be 'wholly or substantially based on that knowledge'. The High Court reiterated it is ordinarily the case, as Heydon JA said in Makita, that:

'the expert's evidence must explain how the field of 'specialised knowledge' in which the witness is expert by reason of 'training, study or experience', and on which the opinion is wholly or substantially based', applies to the facts assumed or observed so as to produce the opinion propounded.'


This decision resolves the question as to the degree to which the expert's training must relate to the specific subject matter of the proceedings. The expertise must be specifically relevant to the precise question for determination rather than generally relevant to the broad field.

This requires careful choice of the expert and proper attention being paid to the preparation of a properly referenced and reasoned report.

The decision will ultimately streamline litigation as 'crummy' reports which have to date been admitted, will be inadmissible and it will be unnecessary to respond with credible expert evidence.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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