629. The Present Law. When an expert testifies as to facts, his evidence is subject to the same rules of admissibility as any other witness. However, an expert is regarded by the law as competent to express opinions relating to the subject of his expertise, where such opinions are relevant to a matter in dispute. This compares with a non-expert who, except in some limited cases, is not permitted to express opinions in this way. This distinction between ‘opinion’ and ‘fact’ is not a clear or precise one. There is a continuum of cases from the certain or indisputable to the uncertain and disputable, from the concrete to the abstract, from the particular to the general. However propositions about Aboriginal customary laws, and indeed any general propositions about the culture, organisation or dynamics of an Aboriginal group or community, would normally be classified as opinions in this sense.
630. Qualification as an Expert. An expert, in the legal sense, is one who by reason of special qualifications is able to express informed opinions on some subject requiring special knowledge or understanding. The courts have been reasonably flexible in accepting particular subjects as fields of expertise, and there is no doubt that the customary laws of an Aboriginal group, and the social anthropology of Aborigines (including the study of their traditions and culture) are areas of expertise in that sense. However, there is uncertainty in the Australian case-law as to the kind of qualifications required for recognition as an expert: is a course of study or formal academic training required, or is it sufficient that the expertise is obtained from experience in the field without any such training? Some Australian cases suggest the need for ‘an organized branch of knowledge in which the witness is an expert’, for ‘study and instruction in some relevant scientific or specialised field [enabling the witness] to express an opinion, founded on scientific or specialised knowledge thus acquired’. On the other hand, other judges have referred simply to the fact that the witness was sufficiently skilled in the subject, irrespective of how that skill was obtained. Thus in Wise Bros Pry Ltd v Commissioner for Railways (NSW), Justice McTiernan simply required proof of ‘sufficient skill and experience to enable [the witness] to express an opinion which would assist the jury to form a correct judgment’ on the issue, and in Clark v Ryan Chief Justice Dixon seems to have adopted a similar view. English courts have always adopted the more liberal approach, and it may be that this view will prevail in Australia.
631. Qualification as an Expert in Foreign Law. The view that a witness may be qualified as an expert in Aboriginal customary laws by reason of ‘habit and experience as distinct from a course of study’ gains support from the analogous question of expertise in foreign law. Aboriginal customary laws are not, of course, foreign to Australia. In one sense, however, they are and will remain ‘foreign’: Australian courts lack ‘organs to know and to deal with’. Aboriginal customary laws just as much as (in many cases, much more than) questions of foreign law. So far as foreign law is concerned, it is established that:
Expert evidence as to foreign law may be given by witnesses who have acquired a special experience therein. It is not necessary that they should be professional lawyers, but it is sufficient if they occupy a post which gives them experience in the law of the foreign country.
The law has adopted a less rigorous approach to the qualification of experts in foreign law than in other contexts. The approach is a flexible one, looking to the substance of the expert’s knowledge rather than to the way in which it was acquired. One reason for this (as for other modifications of the opinion evidence rule) is probably simple necessity. It is unlikely that fully qualified lawyers from foreign jurisdictions will be available in many cases. In the case of Aboriginal customary laws, different considerations apply. ‘Practitioners’ and ‘experts’ in Aboriginal customary laws, if they exist, exist in Australia. But the difficulty of identifying them, combined with the persuasive analogy with proof of foreign law, is likely to lead to similar flexibility by the courts in accepting experts on Aboriginal customary laws.
632. Qualification as an Expert on Aboriginal Customary Laws. Undoubtedly anthropologists, and other persons with formal qualifications in other disciplines related to Aboriginal customary laws and traditions, may qualify as experts. Several issues do however arise.
The Need for Local Experience. As the courts realise, Aboriginal customary laws vary widely throughout Australia. One question is the extent to which someone claiming expertise in the customary laws of a particular group is required to have experience of that group (as distinct from experience of field work among Aborigines elsewhere.) The question arose in Milirrpum v Nabalco Pty Ltd. One of the two anthropological experts is that case, Professor Berndt, had extensive experience of working in the relevant area. The other, Professor Stanner, had considerably less (two visits, totalling 11 days). His evidence was objected to by the Solicitor General on this ground, but was admitted. Justice Blackburn said:
The Solicitor-General did not dispute Professor Stanner’s general qualifications as an anthropologist, but contended that because of his limited experience with the Aboriginals of the subject land he was not qualified to give expert evidence in this case. In such a matter, it seems to me, there can be no precise rules. The court is expected to rule on the qualifications of an expert witness, relying partly on what the expert himself explains, and partly on what is assumed, though seldom expressed, namely that there exists a general framework of discourse in which it is possible for the court, the expert and all men according to their degrees of education, to understand each other. Ex hypothesis this does not extend to the interior scope of the subject which the expert professes. But it is assumed that the judge can sufficiently grasp the nature of the expert’s field of knowledge, relate it to his own general knowledge, and thus decide whether the expert has sufficient experience of a particular matter to make his evidence admissible. The process involves an exercise of personal judgment on the part of the judge, for which authority provides little help … In this case I do not hesitate to rule that Professor Stanner’s general anthropological experience, combined with his special study of Aboriginals of other parts of Australia and his short periods of study in the subject land, qualify him to give admissible evidence on the matters in issue in this case. The shortness of his experience in the subject land may be relevant to the weight of his evidence.
This view is consistent with the general tendency to treat degrees of expertise as going to weight rather than admissibility. No doubt the decision in Professor Stanner’s case was not difficult. A court which refused to hear his views on matters of Aboriginal social and religious life and land-holding would render itself ridiculous. Marginal general expertise combined with lack of local experience might well disqualify a witness, but such a witness would not often be produced anyway. In this area the law seems to be flexible enough to cope with the wide variety of cases.
Persons Not Formally Qualified. A further question is whether it is possible to qualify as an expert by reason of experience of a traditional community, even though formal educational qualifications are lacking. In practice, the courts have heard evidence from persons such as local community advisers, ministers of religion, and government officials. To some extent this is done out of necessity. There might be no-one available with formal expertise in relation to a particular community. Or the evidence may simply be admitted without objection, as an aspect of the laxity and non-observance of the rules which, as Justice Muirhead observed in R v William Davey, characterises much of the case law. But the better view is that a witness may qualify as an expert in the legal sense, by ‘habit and experience’, although in such cases a more searching scrutiny of the nature and depth of the experience is likely to be required before attaching weight to the evidence. This is the desirable position, as the Commission concluded in its Evidence Report, where it recommended that:
Where a person has special knowledge, skill, experience or training, evidence of the opinion of that person based wholly or partly on that knowledge, skill, experience or training is admissible.
In practice the courts do now hear evidence on customary law matters from persons qualified by ‘habit and experience’ in traditional Aboriginal customs and laws. Care needs to be taken in such cases that the scope and expertise is defined and not exaggerated. But the law on this point appears to be, if not entirely clear, at least moving in the right direction.