(i) what is the "matter or event" relevant to the proceeding?
(ii) has the witness seen, heard or otherwise perceived something about the "matter or event"?
(iii) has the witness formed an opinion based on what he/she saw, heard or otherwise perceived about the matter or event?
(iv) is evidence of that opinion necessary to obtain an adequate account or understanding of the witness's perception of "the matter or event"?
32 Only if questions (ii), (iii) and (iv) are all answered affirmatively does the opinion rule not operate to exclude the evidence of opinion.
33 Put more simply, s 78 is designed to permit evidence of opinion that would facilitate the understanding of evidence otherwise relevant and admissible. The section assumes that the matter or event as perceived by the witness is relevant to the proceeding. That is the primary evidence. The opinion evidence is admissible as incidental to an understanding of the primary evidence.
34 Translating those observations to the present question, the relevant matter was the identity of the speakers on the DAT tapes. Mr Fung's perception of that matter did not become relevant until he had formed his opinion as to that identity. Evidence of his opinion was therefore not necessary to obtain an adequate account or understanding of his perception. It was his opinion evidence that was said to render his perception of the matter or event relevant and admissible. Without his opinion, there was no "matter or event" perceived by him, understanding of which would be facilitated by evidence of his opinion. His opinion was the primary, not the incidental, evidence.
35 I am therefore of the opinion that s 78 did not render the evidence admissible.
36 However, that does not necessarily mean that it was wrongly admitted. Notwithstanding the judge's view that, if the evidence were admissible, it was by reason of s 78, and notwithstanding the Crown's concession at trial that Mr Fung did not have specialised knowledge based on his training, study or experience, another alternative is available. A further exception to the opinion rule is provided by s 79 which is in the following terms:
"If a person has specialised knowledge based on the person's training, study or experience, the opinion rule does not apply to evidence of an opinion of that person that is wholly or substantially based on that knowledge."
37 On appeal the Crown argued that Mr Fung's opinion was admissible under this section. While it was conceded that Mr Fung lacked formal qualifications derived from a specialised course of training or study, which would ordinarily be regarded as the foundation for the admission of opinion evidence under this section, it was contended that he fell into the category of "ad hoc expert" recognised in R v Menzies [1982] 1 NZLR 40; R v Butera (1987) 164 CLR 180; R v Eastman (1997) 158 ALR 107; R v Cassar and Sleiman, unreported, [1999] NSWSC 436, unreported.
38 The notion of an "ad hoc expert" appears to have originated in Menzies. The ad hoc expertise in that case was the capacity to decipher tape recordings that were substantially unintelligible to anybody who had not played them repeatedly. A transcript of tape recordings made by a police officer who had, by listening to the tapes many times, acquired such expertise, was held to have been properly put before the jury. The following passage appears in the joint judgment of Cooke , McMullin, Summers JJ and Sir Clifford Richmond:
"If the tape is reasonably short and clearly audible there can normally be no justification for allowing a transcript as well as playing the tape. But there will be cases in which the aid of an expert is reasonably necessary. For example, there may be the use of a foreign language. Or deficiencies in the recording may make it necessary to play tapes more than once to enable a better understanding, yet the sheer length of the tapes may mean that inordinate time would be taken by replaying them to the jury. In such cases, while there should normally be at least one playing to the jury, the evidence of an expert should be admissible as an aid to the jury. He may be a temporary expert in the sense that by repeated listening to the tapes he has qualified himself ad hoc and we see no compelling reason why his evidence should not take the form of production of a transcript which can be admitted as an exhibit. Whether the judge allows the jury to have copies of the transcript, as distinct from merely hearing it read, must be a matter for his discretion in the particular case, bearing in mind the requirements of justice and any risk of unfairness to the accused." (emphasis added)
39 The idea of the ad hoc expert was endorsed by the High Court in Butera. Again, tape recordings were involved. This time the conversations recorded were mainly in the Punjabi language, with some Thai, Malay and English. Parts of the recordings were indistinct and could only be made out after being listened to repeatedly by a person familiar with the languages. Transcripts of the translation made after that exercise had been undertaken were held to have been rightly admitted. In the course of so deciding Mason CJ, Brennan and Deane JJ quoted the passage from Menzies extracted above, and accepted the concept of the ad hoc expert.
40 Both Menzies and Butera were cases decided in the context of jurisdictions in which the rules of evidence were other than those contained in the Evidence Act applicable to the present case. It is for that reason that Eastman and Cassar are important. Eastman was an appeal from a conviction in the Australian Capital Territory, under rules of evidence relevantly identical to those presently applicable, contained in the Evidence Act 1995 (Cth). Cassar was a decision under NSW law and was governed by the same provisions as govern the present appeal. There have, accordingly, been two decisions to the effect that the concept of the ad hoc expert developed under different evidentiary regimes continues to have application under the current NSW evidentiary regime. For myself, I believe s 79 is sufficiently wide to accommodate the idea of an ad hoc expert.
41 The question which next arises is whether it has been shown that Mr Fung was such an expert. This is a matter of some complexity. There is no question that he was an expert for the purpose of the interpretation of the DAT tapes. The question is whether his comparison of the two sets of tape recordings qualified him as an expert for the purpose of identifying two of the three voices he distinguished on the DAT tapes as those of the two appellants, after hearing their voices on the police tape.
42 To characterise this as a simple voice comparison exercise would be to over simplify the exercise Mr Fung undertook. As he said, he listened to the pitch and modulation of the voices, but he also took into account the use of language, accent, and the speed of speech. In the process of translating the DAT tapes he had listened to the voices many times and had, no doubt, acquired (even unconsciously) a familiarity with the voices on those tapes, their accents and speech patterns. On the other hand, the basis he had for comparison was very limited. One criticism, which has some merit, was that the recording of the police conversation with Wong was, except when Wong stated his name in Cantonese, all in English. In relation to Wong, therefore, Mr Fung was comparing a voice speaking in Cantonese on the DAT tapes with a voice speaking in English in the police tapes. In Leung's case most of the conversations on the police tapes were had with the assistance of one of the police interpreters and, in so far as Mr Fung heard Leung speak, he was comparing two recordings in the same language, but, as was pointed out in the cross-examination on the voir dire, in very different circumstances. Further, Mr Fung placed some emphasis on the relative volume of speech, but conceded that he was unaware of the location of the speakers relative to the transmitting device in the garage conversation, or the tape recorder in the police tapes. There were therefore, some deficiencies in Mr Fung's capacity to reach a view about the identification of the voices.
43 The line between opinion evidence and evidence of fact is not always clearly defined. Evidence of physical identification illustrates the point. On the one hand such evidence may be characterised as evidence of fact; but, depending on the circumstances, it may more properly be characterised as evidence of opinion. The ordinary observer would regard evidence given by a man identifying his wife of thirty years as evidence of fact; but a witness who identifies a suspect in a police lineup would be perceived as giving evidence more closely allied to opinion evidence. Where the evidence is more properly seen as opinion evidence, it is frequently opinion evidence permitted to be given by a person without specialist qualifications, but whose specialised experience of the person of whom the identification is made qualifies him or her to give the evidence. It may be that this is a familiar example of an ad hoc expert.
44 Voice comparison is not necessarily a question for expert evidence, although it may be. If the two sets of tape recordings in the present case had been in English, it would have been open to the Crown to have left it to the jury to make their own comparison and assessment of whether the voices on the DAT tapes (or any of them) corresponded to either of the voices on the police tapes. That course theoretically remained open but would have left the jury with a task immeasurably more difficult, given the reasonable assumption that no member of the jury understood either of the Chinese languages involved. The jury would, truly, have been comparing voices only, without the intrusion of language and speech patterns that are part of voice identification.
45 There is another aspect to the task undertaken by Mr Fung that should be mentioned. He was not asked to compare the voices until a few days before the commencement of the trial. There was no specific evidence as to the instruction he was given, but it is an obvious inference that he would have approached his task on the assumption that the two voices on the police tapes were in fact the same as two of the voices on the DAT tapes, and that his role was to determine which voice on the police tapes corresponded to voices identified as M1, M2 or M3 on the DAT tapes. This is a quite different task to determining whether either of the voices so corresponded. If there were any real basis to doubt the assumption, the manner in which Mr Fung was asked to perform the comparison might raise real questions of propriety. The situation is analogous to physical identification by photographs or by a police lineup, in which care must be taken not to suggest that a particular person is the suspect. However, for reasons which will appear below, I am satisfied that in this case the assumption was a valid one. It was therefore proper for Mr Fung to approach his task on the basis that two of the voices on the DAT tapes did in fact correspond to the two voices on the police tapes, and his function was to determine which was which.
46 This means that the ad hoc expertise that he brought to bear was very much more limited than it would have been had the circumstances been different. As I have noted above, Mr Fung had, during the course of translation of the DAT tapes, become familiar with the three voices. It was a relatively small step then to assign parts of the conversation to each of the two appellants.
47 For this limited purpose, I have come to the conclusion that Mr Fung was brought within the category of ad hoc expert. He was familiar with the voices on the DAT tapes from his translation; he was familiar with the accents and use of language of the participants; and he was familiar with the languages in which they spoke, sufficient to enable him to bring a greater understanding to the voice comparison than a person without that language skill would have been. It was for the jury to evaluate such deficiencies as existed and to determine whether they accepted Mr Fung's opinions. It may be assumed that those deficiencies were brought home to them with some force in Counsel's addresses.
48 I am, therefore, satisfied that the evidence was correctly admitted, and that these grounds of appeal fail.
49 Even if that were not so, I would be satisfied that the proviso to s 6 of the Criminal Appeal Act 1912 ought be applied. The evidence that the two appellants, and Law, were the only three people in the premises at the time the tape recordings were made was overwhelming. I say this notwithstanding Wong's evidence that two or three other people had been present. There was no support for that assertion. The evidence of police surveillance was extensive, and although there was no direct evidence from any police officer that the garage door was under observation at all times, there was video evidence which established that nobody else left the house through the garage. That demonstrated conclusively that the three participants in the conversation were the two appellants and Law. The conversation incriminated all three participants. It was not necessary to establish which particular parts of the conversation were attributable to which participant; counsel for Leung conceded, during the hearing of the appeal, that all participants in the conversation inculpated themselves in the offence. Once, therefore, it was established that Leung was a party to the conversation, it must follow that no substantial miscarriage of justice can be shown to have occurred.