Setting precedent since 1959


Expert opinions must comply with the relevant state code established by legislation for the conduct of witnesses. These codes specify that the expert's general duty is to the Court, rather than the party retaining the expert.

An expert witness should provide independent assistance to the Court by way of objective, unbiased opinion in relation to matters only within his or her expertise.

It is the duty of the instructing solicitor to supply the expert with a current copy of the appropriate code. This core principle is followed throughout Australia.


Case description:
A case study in the importance of compliance with overarching obligations, Order 44 and the Expert Code of Conduct by lawyers and experts and the serious consequences that can flow from any non-compliance.

The hapless plaintiff, Mrs Hudspeth, has finally succeeded in obtaining an award of damages against her employer for injuries she sustained in 2005 when she slipped on a soapy mess she was cleaning up in a school toilet block. She commenced her proceedings in 2009. Her success comes after the jury in the first trial found against her. An application made on her behalf in the course of final addresses to discharge the jury had been rejected.

The events giving rise to that application prompted the trial judge, Dixon J, to instigate an inquiry under s29(1) of the Civil Procedure Act 2010 (Vic) (CPA) into the conduct of the plaintiff's lawyers and one of her experts.[1] Their conduct highlights the critical importance of compliance with overarching obligations and O44 concerning the use of expert evidence, and the consequences of contravention. After the jury decision against her, Mrs Hudspeth appealed the trial judge's decision not to discharge the jury.

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Case description:
The plaintiff, Mr Smith, sought orders under Part IX of the Property Law Act 1958 (Vic) adjusting property interests following the termination of a domestic relationship with the defendant, Mr Gould. A single accounting expert was engaged to value property, income and other assets.

Judgement in this case highlighted a number of issues pertinent to the use of expert witnesses. It was found that the expert breached the code of conduct by relying on instructions from legal counsel rather than use his own expert knowledge to ascertain the facts . However, judgement also ruled that the brief provided to the expert was inadequate and did not address the relevant questions. So much so that the evidence was considered useless, and as there was only the one expert engaged, the judge was forced to carry out a valuation of the business himself.

Experts need to be aware of their allegiance to the Expert Witness Code of Conduct and their obligation to investigate and educate the court on the facts of the case (within the parameters of their expert knowledge). A good expert should be allowed to question the brief and request further information so that they are able to come to a fully informed opinion as to the facts of a matter. Counsel also need to ensure their brief addresses the most pertinent questions and ensure that any assumptions they provide are based on logical reasoning deduced from sound evidence.

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Case description:
In Land Enviro Corp Pty Ltd & Ors v HTT Huntley Heritage Pty Ltd & Ors [2012] NSWSC 177 the Court rejected two reports from an expert accountant in support of a damages claim for $170 million because the reports were based upon opinions contained in other reports, which had not been proved.

Expert witness evidence is often based upon assumptions including, in certain cases, the opinions of other experts. The "proof of assumption rule" provides that expert evidence is not admissible unless the assumptions relied upon by the expert are proved by admissible evidence. Failure to prove assumptions, including the opinions of other experts, can be fatal to expert evidence.

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Case description:
Caroline Byrne, an Australian model, was found at the bottom of a cliff at The Gap in Sydney on 8 June 1995. Her then boyfriend Gordon Wood, was convicted of her murder on 21 November 2008. He was acquitted of the conviction in February 2012 in the Supreme Court New South Wales Court of Criminal Appeal.

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The obligations of an expert witnesses may be summarised as follows:-
Expert evidence presented to the court should be, and should be seen to be, the independent product of the expert uninfluenced as to form or content by the exigencies of litigation.

An expert witness should provide independent assistance to the court by way of objective unbiased opinion in relation to matters within his expertise. An expert witness should never assume the role of an advocate.

An expert witness should state the facts or assumptions upon which his opinion is based. He should not omit to consider the material facts which could detract from his concluded opinion.

An expert witness should make it clear when a particular question or issue falls outside his expertise. [More Information: Para. 719]

Case description:
Evidence - Admissibility - Opinion evidence - Section 79(1) of Evidence Act 1995 (NSW) provided that rule excluding evidence of opinion did not apply where “a person has specialised knowledge based on the person’s training, study or experience” and person’s opinion “wholly or substantially based on that knowledge” - Respondent sued appellant in Dust Diseases Tribunal of New South Wales - Respondent claimed he was negligently exposed to unsafe levels of silica while working for appellant - Witness gave evidence about approximate level of respirable silica to which respondent may have been exposed - Opinion treated as admissible to found calculation of numerical or quantitative level of exposure to respirable silica - Whether opinion admissible for that purpose - Requirements for admissibility.

Dasreef v Hawchar is a reminder that when obtaining expert opinion evidence, a party must carefully consider the terms of s79(1) and ask whether the opinion given is based on specialised knowledge which is based on that expert's training, study or experience. Experts occasionally do speculate in their reports, but the practitioner obtaining that expert opinion must be careful to avoid relying on speculation, as the opinion proffered could be inadmissible.

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Case description:
The appellant in this case challenged the rule that an expert witness enjoyed immunity from any form of civil action arising from the evidence he or she gave in the course of proceedings.

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Summary judgement:
The Supreme Court by a majority (Lord Hope and Lady Hale dissenting) allows the appeal. Lord Phillips gives the lead judgment. The majority hold that the immunity from suit for breach of duty (whether in contract or in negligence) that expert witnesses have enjoyed in relation to their participation in legal proceedings should be abolished.

Case description:
The case involved an appeal in regard to a continuing detention/supervision order of a sexual offender being released from Prison. The appellant was found by the primary judge to be a serious danger to the community and she ordered that he be subject to a supervision order under s 17(1)(b) of the Act. 
The expert evidence was provided by two psychiatrists who conducted assessments. He appealed against the making of that order and challenged the expert evidence:

  1. The underlying theories, data, statistical inferences and approaches behind the methodology of the assessment tools were not explained. The operation manuals were not tendered (the chain of facts and assumptions between the methods and opinion were broken and therefore inadmissible; and
  2. Not all the notes, observations and responses were recorded from the patient assessment.

The decision provides some parameters as to how medical and specifically expert psychiatric evidence can be assessed. The clinicians used standardised assessment protocols such as The Risk for Sexual Violence Protocol.

Even though the methodologies and manuals that underpin these assessments were not tendered, the conclusions drawn were admissible.

It was unnecessary for the respondent to tender the operational manuals or other documents describing the models because the evidence was sufficient to describe what the models were directed to measuring, what conclusions were drawn from their application and what limitations there were.

Their opinions and evidence did not become inadmissible merely because they did not document, or give evidence, exhaustively or in detail, as to the appellant’s statement, conduct or behaviour.

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Case description:
Fluctuating and exaggerated claims as to the value of the Application Software -Trademark and copyright infringement - misuse of confidential information - failure to report and pay royalties - collateral abuse of process - contravention of TPA

There were seven experts called to give evidence in this case and two in particular were asked to revise their report numerous times under what Judge Ryan called “a stream of fresh instructions… requesting them to make new and doubtfully available assumptions in order to underwrite a successively larger and larger sum claimed as damages” at [276].

With each report the value of the banking software fluctuated and one expert admitted that her opinion changed at the instruction of legal counsel.

There are two significant points to be taken away from this case. 1) An adverse inference may be drawn from the absence of files or notes of conference where the record shows a meeting took place and the substance of the expert’s opinion substantially changed after the communications, and 2) Any assumptions provided to an expert must be backed by sound evidence with the logical reasons for coming to that assumption explained and not simply doctored to support the sum of damages claimed.

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On 30 June 1986 Sprowles fell at her place of employment on stairs leading from a car park on the roof of the building to the offices below where she worked. Associate Professor Morton, a physicist who specialised in the investigation of slipping accidents, was called as a witness in her case.

In this case, Heydon JA summarised the criteria for admissibility; qualifying who is an “expert” and how they apply their expertise to opinion and the need to demonstrate a clear basis for the opinion.
In an extract from paragraph 85 in this case, it was held that if evidence tendered as expert opinion evidence is to be admissible, it must be agreed or demonstrated that there is a field of "specialised knowledge"; there must be an identified aspect of that field in which the witness demonstrates that by reason of specified training, study or experience, the witness has become an expert; the opinion proffered must be "wholly or substantially based on the witness's expert knowledge"; so far as the opinion is based on facts "observed" by the expert, they must be identified and admissibly proved by the expert, and so far as the opinion is based on "assumed" or "accepted" facts, they must be identified and proved in some other way.

Justice Heydon’s six expert opinion admissibility requirements summarised at [para 85]:

  1. the opinion has to be on an area that the Court accepts is an area of specialised knowledge;
  2. the witness must demonstrate that by reason of specified training, study or experience they are an expert in that area;
  3. the opinion must be confined to matters within that area of expertise;
  4. the expert must state, and the party calling the expert must prove, the facts on which the expert opinion is based;
  5. if any facts relevant to the opinion are assumed they must be identified and proved in some other way; and
  6. the expert must explain how the opinion expressed was reached.

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Case description:
Opinion evidence based on hearsay will be admitted, as an exception to the general rule, if the material is commonly relied on or widely used by members of the expert’s profession.

The case involved the valuation of a mining tenement and the potential cost for a for large scale exploitation of mineral resources.

The expert commissioned a number of consultants to assist his investigations and used these reports and his own specialised knowledge to form his overall opinion and findings. He did not however, explain how he was able to test the reliability or factual basis of the advice he procured.

It was deemed that the procured reports were “specific hearsay” and therefore inadmissible. The Court held that where the inadmissible evidence and the admissible expert evidence were so intertwined because of the lack of proof of primary facts, the entire body of evidence should be rejected.

This case is a reminder that when obtaining expert opinion evidence, the expert must state the factual basis upon which they have based their conclusions. If assumptions are made, they must also be proved.

Hearsay is admissible for experts, provided the hearsay on which the expert relies is of sufficiently general nature to be regarded as part of the corpus of knowledge with which an expert in the field can be expected to be acquainted. Material outside this definition is “specific hearsay”, and is not admissible.

In matters involving specialised knowledge, a court has to rely on the opinion of experts, but it does not have to accept any opinion if it is not supported by objective evidence. An expert opinion should have at the least, a substratum of facts.