(i) Dr McLean
190 Dr McLean sought to give evidence about the condition of Mr Lowe's truck, the adequacy of the tests in the FORS Report and the further information that might be gleaned from it. Also, as the applicants said in closing submissions, much of Dr McLean's account was "based extensively on the effects and consequences of harmonic vibration". They said:
The primary opinion of Dr McLean as to the cause of the problems in the vehicle was the harmonic signature of the truck and the various external excitation sources which inter-reacted with that signature.
He described the nature of the phenomenon, saying:
Every structure vibrates to a certain extent, and in some it is a very small amplitude, but if the amplitudes become very large, and are at the right frequency which is very harmful to where it is transmitted to, such as the driver, it can do very damaging effects.
According to him, its effects could be described as:
… we get symptoms which are higher fuel consumption than a non-vibrating truck …It transfers right down the front tyres, and we then get tyre scalloping … we get … a lot of breakages very early, premature breakages and so forth …the computer management system … simply give up. They just shut down the engine.
Further, Dr McLean said:
… once you get a bend in your shaft or rail, it lowers its natural frequency and it could be as simple as being bent or picked up by the wrong forklift in the assembly system.
He added that drilling holes in different places, the sharpness of drill bits, notching of the metal, cutting sections from the flange, and the tools used to cut the section could all affect the outcome.
191 Subject to the Evidence Act 1995 (Cth), evidence that is relevant in a proceeding is admissible. In order, however, for 'expert' opinion evidence to be admissible, it must fall within s 79 of the Evidence Act 1995 (Cth). This is because opinion evidence is generally inadmissible (see s 76) but s 79 provides that:
If a person has specialised knowledge based on the person's training, study or experience, the opinion rule does not apply to the evidence of an opinion of that person that is wholly or substantially based on that knowledge.
This provision enacts the common law in important respects, although it has consequences of its own. In HG v The Queen (1999) 197 CLR 414 at 427, Gleeson CJ said:
… the provisions of s 79 will often have the practical effect of emphasising the need for attention to requirements of form. By directing attention to whether an opinion is wholly or substantially based on specialised knowledge based on training, study or experience, the section requires that the opinion is presented in a form which makes it possible to answer that question.
192 Section 79 primarily requires:
(a) identification of a relevant field of specialised knowledge;
(b) a showing that, by reason of training, study or experience, the witness has that specialised knowledge; and
(c) a showing that the opinion evidence of the witness is wholly or substantially based on that specialised knowledge.
193 Furthermore, 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. The field of specialised knowledge must be shown to apply to these facts or assumptions. See, generally, Makita (Australia) Pty Ltd v Sprowles (2001) 52 NSWLR 705 at 743-744 per Heydon JA and Sydneywide Distributors Pty Ltd v Red Bull Australia Pty Ltd (2002) 55 IPR 354;[2002] FCAFC 157 at [87], where a Full Court of this Court observed that many of the matters on which s 79 depends involve "questions of degree, requiring the exercise of judgment". Whether or not an expert has the requisite expertise is, however, a question of fact: see Hamod v Suncorp Metway Insurance Ltd [2006] NSWCA 243 at [39]. Where an expert purports to give an opinion that lies outside the field of his specialised knowledge, the opinion will be inadmissible: see, e.g., Allstate Life Insurance Co v ANZ Banking Group Ltd (No 6) (1996) 64 FCR 79 at 85 per Lindgren J and Henscke & Co v Rosemount Estates Pty Ltd (1999) 47 IPR 63; [1999] FCA 1561 at [69] per Finn J.
194 The proof of facts and assumptions on which an opinion is based is not always straightforward. As Heydon JA said in Rhoden v Wingate [2002] NSWCA 165 at [86]:
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 witness must differentiate between the assumed facts on which he or she bases his or her opinion and the opinion being proffered. 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: Arnotts Ltd v Trade Practices Commission (1990) 24 FCR 313 at 347-348 and Idoport Pty Ltd v National Australia Bank Ltd [2001] NSWSC 123 at [13]. 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.
195 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 him: see 'Guidelines for Expert Witnesses' applicable in this Court and National Justice Compania Naviera SA v Prudential Assurance Co Ltd [1993] 2 Lloyd's Rep 68 at 81-82 per Creswell J. 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: see FGT Custodians Pty Ltd v Fagenblat [2003] VSCA 33 ("FGT Custodians") at [12] per Ormiston JA, with whom Chernov and Eames JJA agreed.
196 In the present context, the respondent also drew attention to s 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: (a) be unfairly prejudicial to a party; (b) be misleading or confusing; or (c) cause or result in undue waste of time. It seems that the failure of a witness to comply with relevant 'Guidelines for Expert Witnesses' may be a factor weighing in favour of the exclusion of his or her evidence, since the expert's opinion is infected by failure to understand his or her responsibilities as an expert: compare United Rural Enterprises Pty Ltd v Lopmand Pty Ltd [2003] NSWSC 870 at [15]-[19] per Campbell J.
197 The respondent objected to the admissibility of the opinion of Dr McLean on the basis that:
(a) he lacked the requisite "specialised knowledge"; and/or
(b) he purported to give opinion on matters outside any "specialised knowledge" he may possess as a result of his training, study or experience; and/or
(c) his evidence demonstrated fundamental flaws in its factual basis or in its process of reasoning.
The respondent argued that Dr McLean's evidence should be excluded entirely, alternatively, admitted only for the purpose of providing expert opinion on matters relating to the alleged vibration problems of the Lowes' truck.
198 It was apparently common ground that, as at May 2007, Dr McLean was a senior lecturer in the School of Mechanical, Materials and Mechatronics Engineering, in the Faculty of Engineering at the University of Wollongong. A University of Wollongong website stated Dr McLean's research activities to be "Bulk solids, Handling and Physical Processing" and his "area of specialisation … machine and mechanical system dynamics and evaluation of power and drive requirements for Bulk Solid Handling and Equipment".
199 In his curriculum vitae for May 2007 (Exhibit A31), however, he claimed his research interests were "bulk solid structural and mechanical device interactions" and similar, and "heavy vehicle dynamics and design, nonlinear vibrations, effects of whole body vibration; bio mechanics" (emphasis added). I accept that engineering is a field of specialised knowledge, a subset of which includes knowledge about 'heavy vehicle dynamics and design, nonlinear vibrations, effects of whole body vibration; bio mechanics'. I also accept that this latter subset of engineering knowledge may be relevant to issues arising in the proceeding. The real question is whether or not Dr McLean has been shown to have this claimed knowledge by reason of his training, study or experience.
200 At trial Dr McLean stated that his doctoral thesis was in the area of bulk solids handling, although he had never taught this as a subject. He stated that his usual teaching was:
Engineering dynamics, system dynamics and also engineering analysis, which is mathematical application to engineering, in particular, mechanical engineering … I cover … strength of solids, fluid power, system dynamics and engineering analysis. And from 100 level dynamics right down to pack horse level.
His evidence about his expertise to this point is at best equivocal.
201 Dr McLean's further evidence was to the effect that he had never undertaken his own research or tests on heavy articulated vehicles. Dr McLean said that, with the exception of an undergraduate thesis in 1974, he had not conducted any tests or research on heavy vehicles or their design prior to 1998. He said that his interest in the engineering aspects of heavy vehicles was 'rekindled' in about September 1998. He had not conducted any research on heavy vehicles prior to this date. Nor had he published in the area. In particular, at the time of his correspondence with Andy Read of the FORS regarding the FORS Report, he had not done any testing in relation to the harmonic signatures of heavy vehicles. He had not subsequently undertaken any dynamometer testing of vehicles at Shellharbour TAFE despite at one stage giving a contrary indication. Most, if not all, of his claimed research was undertaken by his students without any actual testing of trucks. He admitted that he had done no testing to establish the effect on the behaviour of a vehicle of the positioning of panhard rods and had no actual knowledge as to how the position of rods would affect vibrations or handling of the vehicle. Dr McLean explained that he
did a lot of on-road testing in vehicles driving up the Hume Highway rendezvousing with trucks coming through from Sydney-Melbourne or down to Yass was another common one. Diversion of trucks from the Newell Highway for me to inspect - to inspect trucks.
He did not elaborate on the nature of these inspections.
202 Furthermore, Dr McLean had not published any articles in refereed journals. He had, however, presented a number of papers (alone and jointly with others, including Mr Lambert) at conferences on aspects of air suspension systems in prime movers, chassis flex, nonlinear vibration phenomena of prime movers, dynamic modelling and the like. Save for some joint publications, there was, therefore, little evidence that he was regarded as knowledgeable by others in the field. His "reports" included some 17 documents that he had elected to provide to the FORS in the period September 1999 to November 1999. He would not have appeared to have supervised any doctoral candidates, although he had supervised other candidates, including undergraduates.
203 Save for his 'inspections' of trucks, by reason of his training, study or experience, Dr McLean's knowledge of the field of 'heavy vehicle dynamics and design, nonlinear vibrations, effects of whole body vibration; bio mechanics' was, at best, theoretical. He explained that it was, in essence, the extrapolation and application by him of his knowledge of "resonance and dynamics … fluid mechanics and fluid power … harmonics effects and how they interact with a mechanical boom light structure". This knowledge was apparently acquired by him in the course of his study of engineering, including his teaching and supervision of students. The evidence regarding truck inspections was sparse. It cannot advance Dr McLean's claim to have specialised knowledge very far, if at all.
204 On the basis of this evidence, I accept that Dr McLean had some specialised knowledge, at a theoretical level, of 'heavy vehicle dynamics and design, nonlinear vibrations, effects of whole body vibration; bio mechanics'. It followed that to the extent he gave his opinion outside this theoretical domain, his opinion was inadmissible. Subject to what follows, practically speaking, in this proceeding, probably the only admissible opinion evidence that he might have given was evidence about the theory of vibration measurement and analysis.
205 The more difficult question is, to what extent, if any, was Dr McLean's opinion evidence wholly or substantially based on his somewhat limited specialised knowledge. For the reasons that follow, it is generally impossible to be satisfied that his opinion was wholly or substantially so based. There are many instances in which it is apparent that his opinion was merely speculation.
206 Dr McLean's evidence did not differentiate between his assumed facts or assumptions and his 'expert' opinion. These assumed facts and assumptions were in most cases unproven and untested. Much of his evidence was virtually incomprehensible, ill-ordered, illogical or manifestly erroneous.
207 For example, Dr McLean expressed an opinion concerning the condition of the applicants' truck. This opinion was apparently based on:
(a) Mr Lowe's account of the alleged defects in the truck;
(b) Two brief inspections of the truck;
(c) Analysis of one segment of data obtained during the instrumented testing as part of the FORS investigation; and
(d) Theory relating to heavy vehicle dynamics and vibration.
These assumed facts and assumptions were never properly identified and proven. The inspections and data analysis were shown to be demonstrably unreliably or wrong; the relevant reasoning processes, questionable; and his account disorganised.
208 Dr McLean's unarticulated assumptions were that, first, the truck actually exhibited the defects alleged by Mr Lowe; and secondly, that there was a correlation between his theories of vibration and the alleged defects. Dr McLean in fact admitted that his theory was a 'generalisation' based on elementary theories of vibration. His opinion regarding the likely cause of the alleged defects in the truck was based on the fact that the alleged defects were apparently consistent with his theory of vibration. Once exposed as merely a generalisation that might account for alleged (but unobserved) phenomena, the untested nature of Dr McLean's opinion becomes apparent. Both Dr Morrison and Mr McPherson made this point. Dr Morrison noted that neither Dr McLean nor Mr Lambert made any objective quantification and assessment of the defects alleged by Mr Lowe and compared these assessments against 'criteria of acceptability'. Mr McPherson also gave evidence as to the untested nature of Dr McLean's engineering assumptions.
209 The fact that Dr McLean had very little, if any, factual foundation for his opinions was emphasised by his very slight first-hand knowledge of the truck - a fact that emerged clearly in cross-examination. Dr McLean stated that he inspected the truck on only two occasions - around Easter 1999 and in September 1999. (The second inspection is likely to have been in 2000, not 1999, bearing in mind Dr McLean's statement that, at the time of the inspection, the vehicle had been parked up for some time and in September 1999 the vehicle was still being used by Mr Lowe.)
210 Dr McLean said that, at Easter 1999, he took a short 'bobtail' test drive with Mr Lowe for around 20 kilometres around Adelaide. He stated that there was "certainly some unusual steering behaviour with that vehicle, when operated bobtail". At trial, however, witnesses for both parties, including Mr Lowe himself, agreed that a bobtail test drive, without a trailer attached, would give no indication as to the actual handling of the vehicle, due to the fact that the truck is designed to be operated with a trailer attached. As Mr McPherson said (and I accept):
.. the vehicles aren't designed … to run continuously bob tail. They are not designed for optimum ride or optimum drive line angles or anything else when they are bob tail. They are designed to run with a load on them. So, they would ride rough if they are in a bob tail condition.