In McNamara v The King [2023] HCA 36 the appellant had been tried jointly with one other defendant, and each blamed the other for the offending. Mr McNamara wanted to include in his evidence allegations of previous criminality by his co-defendant, but the judge ruled that the proposed evidence was inadmissible. This ruling was on the footing that the prejudicial effect of the evidence on the co-defendant outweighed its probative value for the defendant’s case.
Such a basis for excluding evidence is commonly found in evidence laws, and it functions to assist the judge in ensuring that the trial is fair. [1]
Mr McNamara submitted through counsel on this appeal that the judge had no such power in a joint trial. This was rejected unanimously by the Court in two judgments.
Gageler CJ, Gleeson and JagotJJ considered in some detail the interesting [2] history of joint trials [25]ff. Included in this is a period during which it was unclear whether the supposedly unfettered right of a defendant to adduce otherwise admissible evidence was limited by the probative value vs prejudicial effect discretion [49]. The issue was settled by legislation [52]. This came down to the interpretation of the section mentioned at [59] and described in more detail at [1]:
“Section 135(a) of the Evidence Act 1995 (NSW) ("the Evidence Act") empowers a court to refuse to admit evidence, that is relevant and otherwise admissible in "a proceeding", if the probative value of the evidence is substantially outweighed by the danger that it might be unfairly prejudicial to "a party". The question in this appeal is whether "a party" includes a co-accused in a joint criminal trial. The answer is that it does. The Court of Criminal Appeal of the Supreme Court of New South Wales was correct so to hold, and the appeal must be dismissed.”
A joint trial is a proceeding and each defendant is a party, as is the prosecutor [62], and the exclusionary discretion applies [64]-[69], consistently with the operation of other relevant provisions [72]-[75].
Gordon and Steward JJ similarly analysed the legislation, and considered the on-going relevance of common law principles [92]ff, concluding at [109] that, consistently with dicta in other cases, “The existence of the discretion at common law to refuse to admit evidence coheres with the duty of the trial judge to provide an accused with a fair trial.”
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[1] We have a similar provision in s 8 of the Evidence Act 2006 [NZ]. In this, “proceeding” includes joint trials, and “the right of the defendant to offer an effective defence” is taken to mean the right to a fair trial: R v Moffat [2009] NZCA 437, [2010] 1 NZLR 701, (2009) 24 CRNZ 242, Bracken v R [2016] NZCA 79 (leave refused Bracken v R [2016] NZSC 124), Ambler v R [2018] NZCA 245 at [41].
[2] I say “interesting” because the following points are among those mentioned: during the eighteenth century criminal proceedings changed from being essentially inquisitorial to essentially adversarial [25]; at common law a defendant could not give sworn evidence, the right to do so being introduced in 1891 (NSW) and 1898 (England) [26]; the exclusionary rule for when probative value of evidence was outweighed by its prejudicial effect was only developed in 1914 ([27], and see my note here on 8 October 2019, particularly at footnotes 6 and 7); the requirement to acquit if there was a reasonable doubt about guilt was “discovered” only in 1935 [27]; the indictment is a foundational and constant feature of the criminal trial throughout the centuries [28]; in a criminal trial there is one indictment, which may include more than one defendant, and the jury can only determine issues in that indictment [29]. While it has been common to tell juries that where there is more than one defendant charged in the indictment there are separate trials for each of them, this should really be phrased as there are separate “cases” for the jury to consider (cf [36]).
