The criminal courtroom can make innocence look like guilt.
A combination of circumstances persuaded a jury and a first appeal court that a murder had been committed by the defendant, but on second appeal the verdict was held to have been unreasonable, the conviction was quashed and an acquittal entered: Fennell v The Queen [2019] HCA 37 (6 November 2019).
It is worth reading the judgment for an illustration of how to take apart a prosecution case which relies on circumstantial evidence.
From the point of view of the law on how an appeal court may decide whether a jury verdict is reasonable, see [81]-[82]:
“[81] Where a court of criminal appeal is called upon to decide whether it considers that, upon the whole of the evidence, it was open to the jury to be satisfied beyond reasonable doubt that the accused was guilty of the offence charged, the court must not disregard or discount either that the jury is the body entrusted with primary responsibility of determining whether the prosecution has established the accused's guilt or that the jury has had the benefit of having seen and heard the witnesses. [M v The Queen (1994) 181 CLR 487 at 493.] At the same time, however, the court may take into account the realities of human experience, including the fallibility and plasticity of memory especially as time passes, the possibility of contamination of recollection, and the influence of internal biases on memory. [Bingham, "The Judge as Juror: the Judicial Determination of Factual Issues" (1985) 38 Current Legal Problems 1 at 16-18.] The court can also take into account the well-known scientific research that has revealed the difficulties and inaccuracies involved in assessing credibility and reliability. [Fox v Percy (2003) 214 CLR 118 at 129 [31]. See also Devlin, The Judge (1979) at 63; Bingham, "The Judge as Juror: the Judicial Determination of Factual Issues" (1985) 38 Current Legal Problems 1 at 7-8, 10-11; R (G) v Governors of X School [2012] 1 AC 167 at 196-197 [80].] And especially is that so in a case like this where the jury has been subjected to the seductive effects of a species of identification evidence that has in the past led to miscarriages of justice. [See R v Clout (1995) 41 NSWLR 312. See and compare Domican v The Queen (1992) 173 CLR 555 at 561.] ... .
“[82] In an appeal where a ground of appeal is that the verdict was unreasonable or cannot be supported having regard to the evidence, and particularly where the Crown case is based upon a number of matters of circumstantial evidence, it is necessary for the appellate court to assess the whole of the case and to weigh that case as a whole. A circumstantial case cannot be considered in a piecemeal fashion. [R v Hillier (2007) 228 CLR 618 at 638 [48]. And see my note on this case here.] A corollary of this principle, particularly in cases in which the conclusion is not clear-cut, is that a substantial error, or errors, by an intermediate court of appeal in the process of assessing the case as a whole can infect the entire process.”
Here, the first appeal court had made an important error. The credibility of a significant item of evidence (an assertion that a hammer had been lent to the defendant) was greatly over-estimated ([76]-[80], [89]). This error may, I suspect, have occurred because, if true, the evidence would have been highly probative. The treatment of other circumstances as also being more sinister than they were could have led the court to over-estimate the likelihood that the hammer had been correctly identified.
Generally speaking, two steps are involved: first, assessing the credibility - or reliability [1] - of the witness's testimony ("This is the hammer I lent the defendant"), and second, if it is sufficiently credible to satisfy the fact-finder that it is true, the assessment of its probative value on an issue in the case. There is not necessarily a standard of proof for deciding whether testimony is credible, although it is often said that if the evidence must be accepted before a verdict of guilty can be returned then the credibility of that item of evidence must be established beyond reasonable doubt. For less central testimony it is likely that credibility need only be established to a level that "satisfies" the fact-finder that it is true, and here satisfies means on the balance of probabilities. However, this is a rather vexed topic and jurisdictions may differ in how they express the requirement for acceptance of the truth of evidence.
Credibility and probative value are matters specific to the particular testimony that is being considered, but when it comes to assessing the verdict on the accepted evidence, it is all the accepted evidence that must be taken into account. This is why the court can say it is wrong to latch on to one item of evidence and claim that it creates a reasonable doubt about the defendant's guilt. There will be occasions where that can be done, for example if an alibi is accepted notwithstanding that the other evidence strongly supports an inference of guilt. But other than alibi evidence, and also evidence supporting an affirmative defence (where the defendant's actus reus and mens rea are not disputed), in most cases, including Fennell, all the accepted evidence must be considered in deciding whether guilt has been proved beyond reasonable doubt.
In the course of a criminal trial, as evidence of guilt appears to accumulate, further evidence may be given greater credibility than it deserves.
But that’s not all. References by the High Court of Australia in Fennell to Bingham remind us of how Lord Bingham, delivering the judgment of the Privy Council, analysed our notorious circumstantial evidence case, Bain v R [2007] UKPC 33 (10 May 2007), noted here. But the Bain appeal was different insofar as it involved fresh evidence which called into question whether the combined effect of the circumstantial evidence would, in its light, be sufficient to support a verdict of guilty. As there was fresh evidence, it was appropriate to order a retrial. It was not for the appellate court to itself come to a verdict on the new evidence. In contrast, Fennell was not a fresh evidence case. The prosecution relied on categories of evidence - alleged theft, alleged motive, alleged possession of the murder weapon, and alleged opportunity - and each was shown to be unreliable. This was a case of absence of reliable evidence, not a case of assessing on an overall view the probative value of reliable evidence. On finding the conviction unsound the Court could order an acquittal.
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[1] In New Zealand s 28 of the Evidence Act 2006 is relevant where the reliability of a defendant's statement is being considered, and this has been interpreted as meaning that the truthfulness of the evidence can be relevant to assessing its reliability, a position not criticised by the Law Commission in its Second Review of the Evidence Act 2006, NZLC R142 at [6.19]-[6.23]. In R v Wichman [2015] NZSC 198 at [76] the majority in its joint judgment observed in relation to the possibilities that someone who is innocent may be convicted on evidence which turns out not to have been reliable, that these risks "... are inherent in the criminal trial process and cannot be completely avoided. They can, however, be mitigated in various ways; in particular by recognising the risk of unreliability; the provision of a reliability screening process to be carried out by the judge; judicial warnings; jury assessment and the rules as to the burden and standard of proof."