Expert opinion evidence - applying specialised knowledge: Lang v The Queen [2023] HCA 29

We all know how irritating philosophers can be. What would they make of this: “Expert evidence need not be opinion evidence”?

Most statements about the world outside our own bodies are opinions. We can only opine about the reality that casts the shadows on the wall of Plato’s cave. But law is not philosophy.

The sentence quoted above is from Lang v The Queen [2023] HCA 29, per Kiefel CJ and Gageler J at [5]. The case is partly about the sufficiency of proof of guilt, and partly about the admissibility of expert opinion evidence. It is on the latter point that Kiefel CJ and Gageler J wrote, “to elaborate on the common law principles” [4]. Perhaps these judges read the judgments of their colleagues (Gordon and Edelman JJ, who jointly dissented on the application of the law to the evidence in this case, and Jagot J who wrote separately agreeing with the conclusion of Kiefel CJ and Gageler J that the challenged evidence here was admissible) and decided that a bit more was needed.

Principles developed under Australia’s uniform evidence legislation apply also where the law on the admissibility of expert opinion evidence is common law [11]-13]: [1]

“Those principles require that, in order to satisfy the condition of admissibility that the opinion of an expert be demonstrated to be based on specialised knowledge or experience, the inference drawn by the expert which constitutes the opinion be supported by reasoning on the part of the expert sufficient to demonstrate that the opinion is the product of the application of the specialised knowledge of the expert to facts which the expert has observed or assumed. … it is enough that the opinion be demonstrated to be based substantially on that specialised knowledge … Reasoning sufficient to demonstrate that the opinion formed by an expert is the product of the application of his or her specialised knowledge need not be limited to formal induction or deduction. Speculation, however, is not reasoning … Nor is intuition. [The expert’s judgement] requires the justification of reasoned explanation when its conclusions are controverted.” 

The utility or value of an opinion can be addressed in two separate ways, reflecting respectively admissibility and weight: the sufficiency of the demonstration that the opinion is the product of the application of specialised knowledge, and the extent to which the expert’s reasoning is clear and convincing. [15] On the admissibility question, lack of cogency (persuasiveness) is beside the point, [16] or at least it is unless a separate challenge to admissibility is made on the grounds that the probative value of the evidence is exceded by its illegitimately prejudicial effect [17]. Such a separate challenge was not made in this case [18], [25].

Here, the issue was whether the expert had drawn substantially on his specialised knowledge in engaging in the process of reasoning that led to the formation of his opinion.

The majority held that he had. His evidence was a process of inferential reasoning, throughout which he had compared what he had seen - a single stab wound with indicia of multiple thrusts and a turning of the blade in the wound - with what he had previously seen and read of the features of relevant but not identical cases involving suicide and assault [24], [469]. 

In dissent, Gordon and Edelman JJ held that the expert had not shown how his expertise provided a substantial basis for any connection between the facts and the opinion that he expressed [242]. Instead, the asserted connection was speculative [239].

A key difference in the interpretation of the expert’s evidence here is that while the dissenters attached significance to the witness’s description of the wound as “odd”, indicating that the witness was therefore forced to speculate, the majority understood the witness to have used the word “odd” in the sense of not fitting a standard pattern, and the witness was properly applying what he had previously seen and read about to what he observed [23].

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[1] We can expect the reverse to apply in New Zealand: principles developed at common law will inform the case law under the Evidence Act 2006, s 25.

When due process fails - the importance of legal representation: Watson v R (Bahamas) [2023] UKPC 32

A cluster of embarrassing errors in the Court of Appeal of the Commonwealth of The Bahamas led to a successful appeal by the offender in Watson v R (Bahamas) [2023] UKPC 32. I say “embarrassing” because the errors were so fundamental. But, strange to say, oversights of this nature can easily occur.

The appeal Court had quashed a conviction for murder, substituted manslaughter, and in place of the original sentence of death imposed 50 years’ imprisonment. This sentence was imposed without hearing submissions on what the appropriate sentence should be.

There was, therefore, a breach of natural justice amounting to a serious breach of procedural fairness [19]. This was compounded by the Court’s failure to give reasons for the 50-year sentence  [39]. The Court had not accounted for the difference in the law of The Bahamas between murder (for which recklessness as to death is not sufficient for liability) and manslaughter [30]-[31], [35]. Additionaly, the Court had failed to give the offender credit for time spent in custody [44]. Essentially, the Court had acted on too little information.

But confidence in the Court of Appeal’s integrity is reflected by the Privy Council referring back to the Court of Appeal the sentencing determination. In a sense this allows the Court of Appeal to assess the effects of its own error.

The ease with which a court can slip into fundamental error is also illustrated by an appeal (now of historical interest) from New Zealand: Taito v R (New Zealand) [2002] UKPC 15 . Essentially, the Court of Appeal had been over-burdened with administrative tasks, and these seem to have got in the way of the Court’s perception of justice. Legislation - since repealed and replaced [1] - had required the appeal court, through its Registrar, to determine the legal aid applications of prospective appellants in criminal cases. This requirement was accommodated by the practice of the Registrar referring the issue to three judges of the Court who would assess the merits of a proposed appeal and, if no arguable ground upon which the appeal might succeed could be discerned, the Registrar would be directed to refuse legal aid and the appeal would be dismissed without a hearing. This was felt to be most unsatisfactory by many judges, and the complex policy considerations that had come into play in the environment of fiscal constraint were mentioned by Sir Ivor Richardson in “The Courts and Access to Justice” (2000) 31 Victoria University of Wellington Law Review 163. [2] The practice that had been adopted is described in Taito. Although pragmatic, the adopted procedure did not comply with statutory requirements for the hearing of appeals. In none of the 12 consolidated appeals in Taito had the Court heard argument, the appellants were not present or represented, and the judge delivering the determination either had no knowledge of the available information or had previously concluded that legal aid should not be granted as there was no arguable case. There was no exercise of judicial judgement in the disposal of the appeals. Where applicants for legal aid had sought review of their refusal, review was refused without reasons and without requests to be present being met.

The procedure that had been used by the Court of Appeal in Taito was a well-intentioned attempt to find a practical way of dealing with unmeritorious appeals, but as the Board observed, decisions as to merit could only be made after observance of procedural due process. Further, failure to supply some of the appellants with copies of the documents considered by the Court was also a source of discrimination because such an error could not have occurred had the appellants been represented by counsel. This, said the Board, was “contrary to fundamental conceptions of fairness and justice.”

Unrepresented litigants take up a disproportionate amount of the courts’ time, a point noted by Sir Ivor in his article published in 2000 and referred to above, and he added that refusal of legal aid can be a false economy. Representation by counsel is a way of promoting procedural fairness, and absence of representation can result in rights being rendered meaningless. It is easy enough for courts to make fundamental errors, as is illustrated by Watson, above, and representation by counsel cannot be regarded as an indulgence: it is a protection, although not a guarantee of compliance with due process.

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[1] See the Legal Services Act 2011.

[2] Preliminary screening of cases where an appellant sought legal aid by a panel of three judges of the Court of Appeal was a long standing practice, referred to in an earlier article by Sir Ivor: “The Role of an Appellate Judge” (1981) 5 Otago Law Review 1 at 5: “Coming next to criminal cases, because there are so few that involve only matters of law, leave to appeal is ordinarily required. In most cases, too, legal aid is sought and there is a preliminary screening by three of the judges to determine that. If any of the three has any reservations about any of the matters raised, for example, as to the directions given in the summing up, or as to the admission or rejection of evidence, or as to the sentence, then legal aid is granted and the appeal is set down for hearing. If not, legal aid is refused and the application for leave to appeal is called and dismissed without a hearing, unless in the meantime, for example, because of matters raised in further written submissions, the Court decides to hear full argument.” Plainly, unrepresented defendants were expected to know a lot of law.