In Jones v R  HCA 17 (29 April 2009) some interesting issues were mentioned, but they did not need to be decided. They concern the use by one accused of evidence of the propensity of a co-accused.
In this case the proposed evidence was inadmissible as hearsay, and for that reason – together with an error at trial on another point being insignificant – the appeal was dismissed.
Hayne J, in a judgment concurring with that given by the other members of the Court, highlighted the issues for future consideration (37); in summary these are:
- Is it necessary that the co-accused has put his character in issue before the accused can adduce evidence of his propensity?
- How to manage the risk of the trial being diverted into collateral issues about the nature, extent and probative value of the evidence of those propensities.
- Should the rule in R v Pfennig (1995) 182 CLR 461;  HCA 7 apply, or would it lead to diversion of the kind just mentioned?
- When should a ruling that such propensity evidence is admissible be followed by an order for separate trials?
The Pfennig point concerns whether propensity evidence should be governed by the same admissibility requirements as similar fact evidence, especially the need for "striking similarity" and the improbability of an innocent explanation for the apparent link it is sought to establish.
The recent reforms of the law of evidence in New Zealand have provided a framework for addressing these issues. Section 42
Evidence Act 2006 deals with propensity evidence about co-defendants. When will the judge permit the evidence under s 42(1)(b)? Presumably some regard would be had to matters such as those specified in s 43(3) which apply when the prosecution seeks to adduce propensity evidence. The danger of prejudice to the co-defendant has to be considered under s 43(4), and a similar consideration should apply under s 42(1)(b), although in any event the general discretion to exclude unfairly prejudicial evidence pursuant to s 8 would apply to s 42(1)(b).
There is no need for the co-accused to have put his character in issue before the accused may adduce evidence of his propensity. Collateral issues would have to be managed under the requirements of relevance (s 7), prejudice and fairness. There is no requirement of "striking similarity", merely a "tendency to show" a propensity (s 40(1)), and for the common law, see R v Holtz  1 NZLR 667; (2002) 20 CRNZ 14 (CA). As there is nothing to exclude it, the hearsay rule applies to propensity evidence.