Evidence of Bad Character in Criminal ... - Law Commission

The relationship between probative value and prejudicial effect
11.23 The Australian statutory scheme requires the evidence in question substantially
to outweigh the danger of prejudice. Our preferred option merely required the
probative value to outweigh the risk that, if admitted, it might (inter alia) result in
prejudice.
11.24 We were concerned that the result of the Australian statutory scheme “must be
that tendency and coincidence evidence adduced by the prosecution is
sometimes inadmissible even if its probative value outweighs the risk of prejudice. …
[I]f the evidence’s probative value outweighs the risk of prejudice, we see no
reason why it should be excluded merely because it does not substantially
outweigh that risk.” 25
11.25 Mr Justice Tim Smith, Commissioner in Charge of the ALRC Report and a
respondent to the consultation paper, expressed grave concern that the preferred
option failed to give sufficient weight to the risk of wrongful convictions. He
thought that the test proposed was not sufficiently strict:
In paragraph 10.84 the paper refers to what I see as the major
difficulty with the proposal and that is its potential to increase the risk
of wrongful conviction. It is said that this is always a risk with this
kind of evidence but the view of the Commission is that this option
would reduce it “as far as is reasonably practicable”. I would prefer to
phrase the issue slightly differently – whether the option would
reduce the risk of wrongful conviction to an acceptable level. …,
something would be need to be added to the discretion to ensure that
evidence would only be admitted in cases where it is clear that the
probative value will outweigh its likely prejudicial effect.
Ultimately, the problem is that the rule, however it is formulated, will
let into evidence before the tribunal of fact evidence which carries
with it a risk of wrongful conviction because of its prejudicial
effect. … If a balancing test is to be used, however, one which
incorporates the requirement that the probative value of the evidence
substantially outweigh any probative effect would seem to me to be
the minimum requirement if the concern to minimise wrongful
conviction is to be adequately addressed.
11.26 The point made by Mr Justice Tim Smith is that the judge may underestimate
the prejudicial effect of the evidence and, if he or she does so, then the risk of
wrongful conviction is greatly increased. If, on the other hand, the evidence is
only admissible if there is a significant margin between its probative value and its
prejudicial effect then a minor under-estimation will not result in the admission
of evidence which is in fact more prejudicial than probative.
11.27 The counter-argument is that, if there has to be a significant margin, it is possible
for evidence which is more probative than prejudicial to be excluded. In the
25 Para 10.65 (emphasis in original). The omitted section of the para addressed (and rejected)
the possible requirement that the evidence have “significant” probative value.
143