Friday, February 11, 2005

Collateral evidence: rule or discretion?

In contrast to revising hearsay laws that have been considered by the legislature and by the Law Commission, as was done by the House of Lords in R v Hayter - see my blog entry for Monday, February 07, 2005 - the High Court of Australia has resisted an invitation to alter the law. In Nicholls v R [2005] HCA 1 (3 February 2005), a case where the circumstances would have made any such revision obiter, one of the issues involved the collateral evidence rule.

The rule that answers to questions on collateral issues cannot be undermined by cross-examination is potentially a source of injustice if insufficient recognition is given to the exception concerning challenges to the creditworthiness of the witness. How relevant is it that the witness may have been unreliable on matters collateral to the issues at trial? This is obviously an area that should be treated as discretionary, rather than one for the application of rules.

Judges often have to decide between the alternatives of excluding evidence and admitting it, perhaps subject to a warning to the jury about the use to which such evidence may be put. I have discussed this in "The Duty to Prevent an Abuse of Process by Staying Criminal Proceedings" in Robertson (ed), "Essays on Criminal Law: A Tribute to Professor Gerald Orchard" (2004, Brookers Ltd, Wellington) 133. As I pointed out there, such decisions involve the balancing of the probative value of evidence against its prejudicial effect.

Readers who seek more agony may wish to consult my "Probative value, illegitimate prejudice and the accused’s right to a fair trial" (2005) 29 Crim LJ 8, where the balancing exercise involved in this sort of decision is analysed, and it is suggested (I summarise the suggestion) that the decision comes down to admitting evidence if it has significant probative value and if trial fairness would not be compromised.

This would be a satisfactory way of approaching the admissibility of challenges to answers to questions on collateral issues. Of course we are considering something analogous to the other side of the coin because what is usually at stake when the probative/prejudicial exercise is undertaken is the admissibility of prosecution evidence. Usually the collateral evidence rule affects evidence that the defence seeks to adduce, albeit through a prosecution witness. Looking at the decision from this perspective, the first consideration would be: would the evidence be probative on the issue of the witness’s reliability on a matter in dispute in the case? The second consideration would be, would preventing the defence from seeking the evidence affect the fairness of the trial? We can easily see that these come to much the same thing. That is acceptable, because we are not balancing them against each other.

In Nicholls v R at para 53, McHugh J, who would have changed the collateral evidence rule, put it this way:
"… Where the interests of justice are likely to be advanced by admitting evidence tending to destroy the credibility of a witness, courts should hesitate to reject such evidence. Thus, where a circumstance affecting credibility is so inextricably connected with a fact in issue that it will probably determine that fact, a trial judge should generally admit evidence of that circumstance. Evidence of such a circumstance should not be excluded merely because it is not within the established exceptions to the collateral evidence rule. In Natta (1991) 32 FCR 282 at 300 the Full Federal Court concluded that a collateral matter could be pursued beyond cross-examination "in the interests of justice, whether or not it came within any of the traditional exceptions to the rule against evidence on collateral issues."

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