Evidence Bill (2)

The second area of admissibility requiring exercise of judgment has been traditionally formulated as the balancing of probative value against the risk of illegitimate prejudice to the accused that would arise as a result of admission of the challenged evidence. This formula is reflected in clause 8 of the Bill:

8 General exclusion
In any proceeding, the Judge must exclude evidence if its probative value is outweighed by the risk that the evidence will---
(a) have an unfairly prejudicial effect on the outcome of the
proceeding; or
(b) needlessly prolong the proceeding.

The meanings of probative value and prejudicial effect are indicated in clause 39, which deals with a topic commonly the subject of such balancing, called at common law similar fact evidence:

39 Propensity evidence offered by prosecution about defendants
(1) The prosecution may offer propensity evidence about a defendant in a criminal proceeding only if the evidence has a probative value in relation to an issue in dispute in the proceeding which outweighs the risk that the evidence may have an unfairly prejudicial effect on the defendant.
(2) When assessing the probative value of propensity evidence, the Judge must take into account the nature of the issue in dispute.
(3) When assessing the probative value of propensity evidence, the Judge may consider, among other matters, the following:
(a) the frequency with which the acts, omissions, events, or
circumstances which are the subject of the evidence have occurred:
(b) the connection in time between the acts, omissions, events, or circumstances which are the subject of the evidence and the acts, omissions, events, or circumstances which constitute the offence for which the defendant is being tried:
(c) the extent of the similarity between the acts, omissions, events, or circumstances which are the subject of the evidence and the acts, omissions, events, or circumstances which constitute the offence for which the defendant is being tried:
(d) the number of persons making allegations against the defendant that are the same as, or are similar to, the subject of the offence for which the defendant is being tried:
(e) whether the allegations described in paragraph (d) may be the result of collusion or suggestibility:
(f) the extent to which the acts, omissions, events, or circumstances which are the subject of the evidence and the acts, omissions, events, or circumstances which constitute the offence for which the defendant is being tried are unusual.
(4) When assessing the prejudicial effect of evidence on the defendant, the Judge must consider, among any other matters,---
(a) whether the evidence is likely to unfairly predispose the
fact-finder against the defendant; and
(b) whether the fact-finder will tend to give disproportionate weight in reaching a verdict to evidence of other acts or omissions.

The essence of illegitimately prejudicial evidence, as seen from cl 39(4) above, is that it deprives the accused of a fair trial, by causing bias or improper use of evidence.

The balancing of probative value against the risk of illegitimate prejudice has caused great difficulty in practice, because it is a fallacy to say that probative value is something that can be put in opposition to the accused’s right to a fair trial. These are not things that can be weighed against each other.

Useful guidance can be obtained from the recent evidence law reforms in England. Whereas the Law Commission of England and Wales, in its Report of October 2001, "Evidence of Bad Character in Criminal Proceedings", proposed a draft Bill containing , in clause 8, the weighing of risk of prejudice against probative value, that proposal was not enacted. The Criminal Justice Act 2003[UK], s 101(3), contains the revised law:

"The court must not admit evidence … if, on an application by the defendant to exclude it, it appears to the court that the admission of the evidence would have such an adverse effect on the fairness of the proceedings that the court ought not to admit it."

This avoids the fallacious weighing, although it may be accused of vagueness as to how much unfairness is sufficiently adverse to require exclusion of the evidence. That point will be considered in the next blog entry in this series on the Evidence Bill.