Authority on expert evidence as an exception to the opinion rule
15 There is a significant overlap in authority on so-called expert evidence relied upon by the parties, with each relying on many of the same cases in aid of the outcome they sought. A part of the reason for this is that many of those cases are something of a curate's egg, permitting different outcomes to be supposedly arrived at depending on emphasis and characterisation.
16 Many of the general principles emerging from a number of the authorities require some regard to be had to the type of "expert" evidence being considered. It is also relevant to have regard to how the evidence in question had been sought to be used in those cases. That approach enables some arguments to be sustained and others not when applied to the different facts and circumstances in this case.
17 The two seminal cases of the High Court on expert evidence are HG v The Queen [1999] HCA 2; (1999) 197 CLR 414 and Dasreef Pty Ltd v Hawchar [2011] HCA 21; (2011) 243 CLR 588. HG and Dasreef (along with many intermediate appeal court decisions) reveal that when there is present:
(a) a real question as to whether a claimed or required specialised knowledge is possessed by a witness sought to be relied upon to express an opinion by way of exemption to the opinion rule; or
(b) a real question as to whether such an accepted expertise has been applied to produce such an opinion sought to be relied upon,
strict adherence to the formal requirements of s 79(1) may be required so as to enable an opposing party and the Court to examine and test whether such a fatal defect exists.
18 For the reasons that follow, no such real issue exists in this case. In those circumstances, a degree of departure from strict adherence to the formal requirements to be implied from s 79(1) may more readily be acceptable or otherwise pose no proper barrier to the admission of the impugned evidence. Much may depend on the facts and circumstances of the case and the nature and presentation of the evidence under challenge.
19 In HG, the appellant was convicted of two offences of having sexual intercourse with a child under the age of ten years and had been sentenced to a term of imprisonment. The complainant was the daughter of the appellant's de facto wife. The central issue of the appeal to the High Court was the trial judge's ruling to reject defence expert evidence of a psychologist. The appellant sought to rely upon that evidence to avail himself of a statutory exception to a provision which rendered prior sexual history evidence of a victim inadmissible.
20 The psychologist in HG had given evidence at the committal proceedings in the form of a written report, together with oral evidence, parts of which provided further explanation of the contents of the written report. In short, the key part of the psychologist's written report concluded that the plaintiff had in fact been sexually abused, but by her biological father some years earlier and not by the appellant at the time alleged by the complainant. The psychologist was described by the High Court as having degrees in Arts, Education and Psychology and had experience working with children, including counselling and dealing with children that had been sexually abused.
21 Though the primary focus of the appeal was on the particular statutory exemption, Gleeson CJ considered the psychologist's evidence by reference to s 79 of the Evidence Act (of New South Wales, which is relevantly the same as the Commonwealth Act). Gleeson CJ opined that the expert's evidence did not distinguish between opinions and the assumed facts underpinning those opinions and ultimately did not meet either limb of s 79(1).
22 Chief Justice Gleeson at 427 [39] stated (emphasis added):
The opinions of [the psychologist] were never expressed in admissible form. An expert whose opinion is sought to be tendered should differentiate between the assumed facts upon which the opinion is based, and the opinion in question (36). Argument in this Court proceeded upon the basis that it was possible to identify from [the psychologist]'s written report some facts which he either observed or accepted, and which could be distinguished from his expressions of expert opinion. Even so, 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.
23 This paragraph must be understood in its proper context: while form is important when considering the provisions of s 79, requirements of form may be more easily satisfied or of lesser importance in a given case. In HG, the psychologist's evidence was a complex narrative that provided a complete and alternative explanation to the version of events propounded by the complainant, rather than a mere opinion as to whether or not a particular event had occurred. The High Court indicated that in those circumstances, as a practical matter, form will be important to enable an understanding of the asserted expert's relevant experience, the underlying assumptions and the intermediate and final conclusions drawn as distinct from inference and speculation.
24 In providing an account of the most likely narrative, the impugned evidence in HG fell outside the bounds of expertise expected of a psychologist and it could not be distinguished which views were wholly or substantially based on training, study or experience or simply personal opinion.
25 Mr Van Homrigh's evidence does not enter the same territory of providing an alternative and wildly differing narrative, or engaging in speculation and inference that cannot be distinguished from reasoned conclusions. The field of accounting and the task asked of Mr Van Homrigh is arguably less subjective and less susceptible to inference and speculation as compared to the field of psychology. In further contrast to this case, the opinions of the expert in HG were never expressed in admissible form. Mr Van Homrigh's evidence is plainly in admissible form. For all of these reasons, strict adherence to the formal requirements of s 79 is of lesser importance in this particular case.
26 In Dasreef, the plaintiff sought damages for personal injury against his employer in the Dust Diseases Tribunal of New South Wales. He had been a labourer and stonemason who had been exposed to silica dust at work and had contracted silicosis. The live question was the extent of the exposure, and whether it was sufficient to provide a causal connection to the contraction of silicosis. The plaintiff relied upon the evidence of a retired academic, who was a qualified chemist and qualified engineer, purportedly to provide that sufficient measurement of exposure so that the primary judge would be able to find the required causal connection.
27 The academic gave evidence estimating silica dust concentrations that would arise in a particular mode of work encountered by the plaintiff. This evidence was used by the primary judge in combination with other evidence about the effectiveness of a mask used and about daily exposure periods to arrive at an estimated time-weighted average exposure over a 40-hour working week. That combination of evidence was used to establish that the plaintiff's estimated level of actual exposure to silica dust exceeded the relevant work health and safety standard, giving rise to the requisite causation.
28 In ultimately rejecting the evidence as not falling within the exception to the opinion rule contained in s 79(1) of the Evidence Act, the High Court focussed on the precise way in which the expertise and the asserted opinion arrived at had been expressed and characterised. This analysis revealed what were found to be fatal defects of both relevant expertise and purported expert conclusions reached - that is, a failure to satisfy either limb of s 79(1).
29 The High Court in Dasreef found that the academic did not give evidence that his study, training or experience enabled him to do more than provide a ballpark figure estimating the amount of respirable silica dust to which a worker would be exposed if that worker was using an angle grinder in the manner depicted in a photograph and video of the plaintiff: Dasreef at 604-5 [39]. This was not the same as having expertise to give, and in fact giving, an opinion as to the numerical or quantitative level of exposure to respirable silica in fact encountered by the plaintiff in working for his employer. The academic, in effect, gave evidence about what measures could have been taken to prevent the plaintiff contracting silicosis if he was exposed to respirable silica 1,000 times greater than the permissible level, not whether he had in fact suffered that level of exposure: Dasreef at 603 [34].
30 The vitally important aspect of this conclusion by High Court in Dasreef is that well-recognised fields of expertise - chemistry and engineering - did not enable the academic to express views that extended beyond those particular areas unless clearly connected by study, training or experience. The academic had only seen the use of an angle grinder in the way depicted once before, and gave no evidence that he had ever previously measured, or calculated inferentially, the amount of respirable dust to which such an operator would in fact have been exposed. He simply did not have the expertise to reach the conclusion relied upon.
31 The High Court ultimately held that it was not so much that the academic had gone too far, but rather that his evidence had not gone as far as had been held in the courts below, nor as far as was needed to enable the primary judge to reach the necessary conclusions founding liability on the part of the employer. This was very much a finding based on the particular facts and circumstances of that case. The ratio of the High Court majority decision in Dasreef must be read in that way. In particular, that is the context in which the entirety of Dasreef at 604 [37] must be read, with a particular focus in this case on the passage in bold:
It should be unnecessary, but it is nonetheless important, to emphasise that what was said by Gleeson CJ in HG (and later by Heydon JA in the Court of Appeal in Makita (Australia) Pty Ltd v Sprowles (51)) is to be read with one basic proposition at the forefront of consideration. The admissibility of opinion evidence is to be determined by application of the requirements of the Evidence Act rather than by any attempt to parse and analyse particular statements in decided cases divorced from the context in which those statements were made. Accepting that to be so, it remains useful to record that it is ordinarily the case, as Heydon JA said in Makita (52), 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". The way in which s 79(1) is drafted necessarily makes the description of these requirements very long. But that is not to say that the requirements cannot be met in many, perhaps most, cases very quickly and easily. That a specialist medical practitioner expressing a diagnostic opinion in his or her relevant field of specialisation is applying "specialist knowledge" based on his or her "training, study or experience", being an opinion "wholly or substantially based" on that "specialised knowledge", will require little explicit articulation or amplification once the witness has described his or her qualifications and experience, and has identified the subject matter about which the opinion is proffered. (emphasis added)
32 An immediate distinction can be drawn between the purported extended use of expertise in Dasreef, and Mr Van Homrigh's evidence. While Mr Hart seeks to position his case in the same way, by accepting Mr Van Homrigh's expertise, but denying its application, the first aspect of the Dasreef problem is absent. That is because tracing and explaining flows of money is, in my opinion, plainly part and parcel of both the expertise and application of expertise of a forensic accountant. This is quite unlike a chemist and engineer stepping outside his field of expertise, and giving evidence, which was then used by the trial court to reach conclusions beyond both what he in fact said and beyond what he was capable of saying.
33 Mr Van Homrigh's evidence is not merely in the form of financial records which this Court can read for itself, and his opinion is not based solely on those records and nothing more in the way of specialised knowledge: see ASIC v Rich [2005] NSWSC 149; (2005) 190 FLR 242 at 309-310 [284]. Nor is it stating what is otherwise obvious from the bare collection of records: see Quick v Stoland (1998) 87 FCR 371 at 382-3. To the contrary, Mr Van Homrigh's evidence entails drawing information from a range of records, presenting that information in a coherent and interrelated form, and drawing conclusions and expressing opinions as to the source and destination of moneys which are the very funds upon which the impugned assessments are based.
34 This is a situation in which analysis of the various records was required in order to reach the conclusions advanced and relied upon by the Commissioner: see Quick v Stoland at 382-3. While a judge might have been able to reach the same conclusion if given enough time, for the additional reasons advanced below that does not deny the evidence its essential quality of being expert evidence.
35 The measure of whether evidence falls within s 79(1) is not whether the task can in theory be performed by a sufficiently capable judge in the particular area given enough time and effort, without the application of accepted specialised knowledge, but whether the task is in fact carried out by the genuine application of such accepted specialised knowledge that adds the required level of value to the evidentiary and judicial process. In some cases that distinction may be difficult to draw. Issues of sophistry and spurious expertise may arise in some cases. However the distinction remains real and necessary. In my opinion, that was the distinction required to be drawn in this case, and was sufficiently drawn by the Commissioner.
36 It is not to the point that a mere lawyer, sitting as a judge, might, if given enough time and lay instruction or other help or guidance, even by a well-informed barrister, be able to carry out and perhaps even understand flows of money and form views about the source and destination of funds of the kind that has arisen in this case. In my opinion, that is not what was being referred to in ASIC v Rich as being something that a judge can do or read and understand for him or herself.
37 Nor is it, at least in this case, "otherwise obvious" as referred to in Quick v Stoland. The idea of a judge being able to do something him or herself, or being obvious, as a measure of evidence not being of a kind contemplated by s 79(1), is to be understood as something which could be done by any judge in a reasonable amount of time, perhaps allowing for or requiring some knowledge or experience in certain specialised areas of litigation.
38 To illustrate the point, with lay assistance a judge might be able to be taught to carry out a simple medical procedure such as suturing a wound. That has been known to be carried out in emergencies by lay people, especially with remote guidance. But that would not make the actions of a medical practitioner any less expert in performing such a procedure. Nor would it deny that such a medical practitioner giving evidence about how such a procedure should be performed would be other than evidence of an opinion that is wholly or substantially based on accepted specialised knowledge.
39 That said, evidence is not expert evidence within the terms of s 79(1) merely because it makes judicial life less onerous. Nor does merely explaining or making complex or voluminous evidence easier to understand turn the process by which that is presented into evidence within s 79(1). To the contrary, that may be a mechanical non-expert process, even if complex, for which reliance may be placed on summaries adduced in accordance with a direction sought and obtained pursuant to s 50 of the Evidence Act. Of course, in some cases, expert evidence will also collaterally fulfil the function of s 50, but that side benefit does not of itself deny such evidence any s 79(1) character that it otherwise possesses.
40 Nor is it necessarily to the point that the conclusions able to be established are not disputed, or may be the subject of formal agreement, unless that agreement precludes the evidence being adduced at all: see s 191(2)(b) of the Evidence Act. A party may be entitled to prove something that an opposing party does not dispute, if only because the process of proof aids in ensuring a judge has the necessary understanding of what has actually happened, or its factual or legal significance.
41 Of course, if evidence sought to be adduced, and ultimately admitted, is unfortunately ultimately found to have been unnecessary, or otherwise a waste of time, that may need to be addressed by an appropriate costs order. That residual sanction does not mean that a party is free to adduce whatever evidence he, she or it chooses, merely because it passes a threshold of admissibility: sections 37M, 37N and 37P of the Federal Court of Australia Act 1976 (Cth) preclude such a cavalier approach.
42 On balance, I consider that Mr Van Homrigh's evidence does constitute expert evidence sufficient to cross the threshold necessary to be made admissible under s 79(1) of the Evidence Act. Such things as weight, value, reliability and reliance are other matters that may need to be determined at trial. I therefore concluded that Mr Van Homrigh's evidence met the necessary threshold for admissibility. Accordingly it will be admitted into evidence at the trial.
43 In this case, the interlocutory application to exclude Mr Van Homrigh's evidence was brought well before the trial. I do not make that observation by way of criticism. Forensic choices have to be made in litigation. Not all of them will be vindicated. I am satisfied that the application was legitimately brought and for a bona fide purpose, albeit unsuccessful. In those circumstances and because the course of the trial has not yet unfolded, I am of the view that the usual outcome of costs following the event of an interlocutory application (see r 40.04 of the Federal Court Rules 2011 (Cth)) should give way to costs being reserved pending the ultimate outcome of the matter.
44 For the above reasons, the interlocutory application was dismissed, and costs reserved.
I certify that the preceding forty-four (44) numbered paragraphs are a true copy of the Reasons for Judgment herein of the Honourable Justice Bromwich.