Australia: Expertly Unqualified - Warning On Expert Evidence

Last Updated: 27 April 2009
Article by Jocelyn Kellam

Lowe v Mack Trucks Australia Pty Limited [2008] FCA 439

  • The significance of independent expert evidence and adequate pleadings are highlighted in this decision.

Lowe was a partnership, operating an interstate transport business carrying goods by truck along the east coast of Australia. It bought a new Mack CH Elite Highway prime mover and on the first run noticed problems with the prime mover. The litany of alleged complaints was so bad that Lowe approached Mack Trucks about the possibility of returning the prime mover on a walk-away basis. Lowe's complaints about the prime mover led to it being included in a group of vehicles selected for examination as part of an inquiry by the Federal Office of Road Safety into aspects of long-haulage road transport operation in Australia. Lowe eventually formed the view that the ongoing defects in the prime mover were so bad that it parked it and walked away from it.

A product liability action was commenced as a class action but proceeded to trial as an individual matter with Mack Trucks being sued for breach of contract, negligence, breaches of sections 52, 53(a), 53(aa), 53(ea) and 53(g) of the Trade Practices Act, unconscionable conduct contrary to sections 51AA and 51AC of the TPA, and breaches of the Fair Trading Act 1987 (SA) and the Sale of Goods Act 1895 (SA). The key allegations were:

  • misrepresentations by the Mack Trucks' representative, including that the prime mover was suitable for its interstate long-haul transport business and would "drive like a car";
  • the prime mover was beset with rough ride, poor handling, poor performance, vibration, darting, wandering, a litany of breakages, inordinate component failures, premature replacement of parts and was not fit for purpose;
  • 26 instances of failure in the design and construction process including a bowed and bent chassis, defective cab mounts, inadequate leaf springs, incorrect axle camber and inherently defective air bag suspension systems; and
  • at the heart of the allegations was a general product liability problem arising from inadequate design with all large prime movers that had longer wheelbases, taller cabins, more powerful engines, loads with higher centres of gravity and airbag suspension. It was asserted that this class of vehicle suffered from a potential instability generally and there was an inherent problem of excitation of harmonic signature resonance vibrations which arose from inter-reaction with external sources - that is, the prime mover would inherently vibrate with highway usage.

Expert evidence issues

The case revolved around a significant volume of technical engineering evidence. As a general proposition, for expert opinion evidence to be admissible:

  • there must be identification of a relevant field of specialised knowledge;
  • it must be shown that, by reason of training, study or experience, the witness has that specialised knowledge; and
  • it must be shown that the opinion evidence of the witness is wholly or substantially based on that specialised knowledge.

In applying those broad propositions to the technical evidence from numerous engineers, Justice Kenny of the Federal Court made these useful observations for evaluation of experts' evidence:

  • Area of expertise: There must be a proven expertise in the relevant area or areas in contention - in this case the judge considered that there several disciplines and sub-disciplines that could be the subject of expert evidence and confined to particular witnesses to relatively narrow areas (eg. particular types or classes of vibration);
  • Expression of expert opinion: For any opinion that is wholly or substantially based on specialised knowledge based on training, study or experience, compliance with the rules necessitates that the expert opinion is presented in a form which is referable to the specific issue in contention;
  • Objectivity: A want of independence, in the case of an expert witness said to be affected by interest or bias, tends to affect the weight to be given to his or her opinion. It is also accepted that an expert witness is not an advocate for a party and has a paramount duty to the court and not to the person retaining the expert - in this particular case the court found that the applicant's experts lost all objectivity in respect of the case and that there were certain personal agendas which they wish to further;
  • Information sources: The witness must disclose in what way, if any, the opinion is based on information communicated by another person. If this is not done, then the opinion may be inadmissible or carry diminished weight. More generally, the reasoning on which the opinion is based must be sufficiently intelligible and transparent to enable the court to form its own assessment about the cogency of the opinion;
  • Statement of assumptions: The witness must differentiate between the assumed facts on which he or she bases his or her opinion and the opinion being proffered. The facts and assumptions on which the witness bases his or her opinion must be identified and proved, and constitute a proper foundation for the opinion expressed. In this particular case, apart from specialised engineering evidence expert evidence was called as to damages and the court rejected the evidence because:
    • the expert's key assumptions depended on the applicant's unsubstantiated allegations of fact; key assumptions had no reasonable basis in the evidence or elsewhere; and
    • key assumptions were contrary to the facts even as the applicant alleged them to be.
  • Application of expertise: The field of specialised knowledge must be shown to apply and be applied to the facts or assumptions, that is there must be an application of expertise to the establish matrix of material;
  • Underpinning evidence: When assessing the admissibility of expert opinions, it is not the case that an opinion is only admissible if at the close of the case of the party relying on it the evidence establishes each of the assumptions on which it is based on the balance of probabilities. The primary evidence relating to those assumptions might be controversial. Which parts of the primary evidence are to be accepted, and what the correct conclusions from the primary evidence are, are matters for the trier of fact at the end of the trial. The opinion evidence may be admitted if there is evidence which, if accepted, is capable of establishing the truth of the assumptions. The weight given is clearly predicated on the findings actually made; and
  • Discretion: In the context of this case, the respondent also drew attention to section 135 of the Evidence Act 1995 (Cth), which confers a discretion to refuse to admit evidence if its probative value is substantially outweighed by the danger that the evidence might:
    • be unfairly prejudicial to a party
    • be misleading or confusing; or
    • cause or result in undue waste of time.

Justice Kenny took the unusual step of disallowing the applicant's expert evidence on most areas of the relevant experts' disciplines.


Mack Trucks' defence was comparatively straightforward, admitting:

  • it had sold the prime mover for use in interstate long distance goods transport;
  • the representations were made as to its suitability and riding like a car;
  • there was no inordinate number of component failures, and it took a conservative approach to complaints in the warranty period, replacing parts whether or not it was strictly necessary to do so;
  • a number of Mack Trucks employees could find nothing wrong with the truck, although they took it for test drives; and
  • after Lowe parted with the truck, another operator used the truck successfully, without problem, for another 600,000 kilometres.

Mack Trucks asserted that the misleading conduct claim was fundamentally flawed, asserting that there were only two representations alleged to be relied upon. One of them added nothing to the claim beyond merchantable quality and the other was mere puffery and was not ever relied upon.

The court accepted that there were at least three significant deficiencies in the applicant's pleading of its misleading conduct claim:

  • The pleading did not specifically identify the basis upon which alleged representations were untrue. No part of the pleading stated precisely in what respect or respects either of the representations relied on was false;
  • Notwithstanding the apparent invocation of section 51A of the TPA, Lowe did not, at any stage, indicate which of the 16 representations alleged were representations in respect of future matters;
  • Lowe provided no particulars of the damages that it alleged flowed from this supposed misleading and deceptive conduct; and
  • In the context of talking to a professional mechanic and truck driver of 20 years' experience in 10 different trucks of this grade, that driving the truck was like driving a car was in the nature of commendatory puffery and not a representation of an actionable kind. Further, no damages flowed from the statement.

The court, in addition to finding against Lowe, also found the claims of misleading conduct and misrepresentation had not been pleaded correctly and dismissed the case on that ground alone.

Lessons to be learnt

In cases where there is technical evidence underpinning a product liability claim, it is essential that evidence be given in an admissibly form by an appropriately instructed and briefed expert.

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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