28 It is clear from the foregoing that the intended evidence of Mr Curtin involves a significant component of judgment by him where he is required to determine whether a particular cash payment or deposit is matched by a previous cash withdrawal by the same accused. To a material extent those judgments by Mr Curtin involve assumptions made by him as to the spending behaviour of "normal" people. Mr Curtin has not been able to identify any particular specific training, or field of learning, on which those assumptions were based. Certainly as a forensic accountant he has undertaken a number of cash flow analyses, particularly with the Fraud Squad. No doubt those analyses have involved him developing and utilising assumptions and criteria particular to each individual case. To that extent Mr Curtin may well have developed a level of expertise in identifying and refining criteria and assumptions which are appropriate to cash flow analyses and similar exercises. However, it must be borne in mind that the criteria and assumptions that lie at the heart of Mr Curtin's evidence, in respect of some of the cash payments and deposits, are assumptions and criteria relating to the spending conduct of "normal" individuals in our community. Mr Curtin did, at an undergraduate level, undertake some statistical study which may have given him a baseline of learning in respect of the community's spending habits. However, that study was undertaken more than two decades ago. Further, and more importantly, the cross-examination of Mr Curtin, on a number of hypothetical situations put to him, reveal that the type of criteria and assumptions which he used were based on his own views, and were not derived from any field of expertise or learning.[28] As Mr Curtin fairly conceded, his fundamental response was to make a "judgment call" relying on concepts of "reasonableness and fairness".
29 Mr Curtin frankly conceded that where there was not an obvious match, or lack of match, in respect of a cash payment, this his analysis was based on "reasonableness and fairness". He said, "It is based on my reasonable approach to transactions, as to how transactions occur."[29] Again, that approach necessarily involves Mr Curtin's views and assumptions as to the spending behaviour of ordinary people.
30 In my view the assessment of how an "ordinary" person might have spent funds withdrawn by him, and which was made by him at a specific time before a particular cash payment, is essentially an assessment which a jury can make without the aid of an expert. The essential role of a jury is to bring into the court's adjudicative processes the common sense, proportion and reasonableness of the normal person in our community. It is precisely those qualities which are called upon by Mr Curtin in making assessments in respect of some of the cash payments and deposits. In that respect the views of Mr Curtin are no more valid than the views of anyone else in our society including that of a juror. There is nothing in the evidence before me that suggests that those views are derived from a specialised area of learning or experience of Mr Curtin. Nor has it been shown to me that, where he has been required to make assumptions as to the ordinary spending behaviour of individuals, there is a specialised field of learning upon which an appropriately qualified expert might draw. Further, and importantly, it has not been shown to me that, in respect of those cash payments in respect of which a "judgment call" must be exercised, a jury is unlikely to make an incorrect judgment without the aid of "expert" evidence.
31 In those circumstances there is a clear risk that, if Mr Curtin were permitted to give evidence which involved his assessment of the spending habits of "normal" individuals, that evidence might be wrongly perceived by a jury as having superior weight to the jury's own views and assessments, because of his status as an "expert".[30] It is for that very reason that courts are particularly astute to ensure that experts are confined to giving evidence in respect of areas to which their particular expertise pertains, and in particular are confined to giving evidence in respect of matters without the assistance of which it is unlikely a court would be capable of reaching a correct conclusion.
32 For those reasons, I have come to the conclusion that it would be inadmissible for Mr Curtin to give evidence based on assumptions and assessments made by him relating to the spending conduct of "normal" individuals. Those assumptions have not been shown to me to be assumptions which are within the province of some specialised field of learning, experience or practice. Nor has it been proven to me that, in any event, Mr Curtin has any sufficient expertise to qualify him to give evidence as to the ordinary spending conduct of "normal" individuals.
33 The arguments made by the accused as to the admissibility of Mr Curtin's evidence were wider and more extensive than questions of his expertise to give evidence based on his assessment of the likely spending habits of ordinary people. Indeed, at some stages of his submissions, Mr Young, on behalf of Cox, went so far as to contend that Mr Curtin would not be qualified to give evidence beyond collating and reorganising financial date relating to Cox.
34 It is not appropriate nor possible for me to make any ruling beyond the two conclusions which I have already expressed. The assumptions made by Mr Curtin, and which were the subject of the principal focus of cross-examination and indeed submissions, concerned his evidence, on the voir dire, that his methodology consisted of interpreting financial data based on assumptions by him as to the spending habits of "ordinary" people. It has been appropriate that I rule on that aspect of Mr Curtin's evidence, since it was sufficiently agitated before me to enable me to do so. However, in any event, it will be necessary for Mr Curtin's evidence to be reformulated so as to properly identify the assumptions and criteria utilised by him in reaching his conclusions. It would be premature for me to embark on any further ruling, or to make any further comments, on any other assumptions to be made by Mr Curtin, unless and until he clearly identifies those assumptions in any further report to be prepared by him.
35 In addition, as I have already noted, each accused has made submissions that, even if the evidence of Mr Curtin were admissible as expert opinion evidence, nevertheless I should rule against its admission at the trial of this proceeding, based on an exercise by me of my discretion to do so. Each accused submitted that, for a number of reasons, the probative value of the intended evidence of Mr Curtin is limited. On the other hand, it has been submitted, its prejudicial value, in relation to each accused, is significant. Thus each accused submitted that I should reject the evidence based on an exercise by me of my discretion.
36 Regrettably, I am not in a position to make a ruling, or indeed offer any comments, in relation to that aspect of the accuseds' submissions. An appropriate assessment of the potential probative value, and the prejudicial value, of the evidence of Mr Curtin, will ultimately depend on the form in which it is to be given at the trial of each accused. It is not possible for me to make any appropriate assessment of those matters unless and until the evidence of Mr Curtin is properly reformulated in light of the matters to which I have referred above.
Conclusion
37 For the reasons which I have set out above, I according rule as follows: