Commentary on Sections Part 11 - Evidence Chapter 1 : Evidence of Bad Character Section 100 – Non-defendant’s bad character
359.Section 100 sets out the circumstances in which, outside the alleged facts of the offence and its investigation and prosecution, evidence can be given of the previous misconduct of a person other than a defendant in the proceedings. This might be a witness in the case or a victim but extends to any other person as well. Evidence of their bad character is not to be given without the permission of the court - Section 100(4) - and can only be given if it meets one of three conditions. These are:
	it is important explanatory evidence,
	it is of substantial probative value to a matter in issue and that issue is one of substantial importance in the case, or
	the prosecution and defence agree that the evidence should be admitted.
360.The term “explanatory evidence” is used to describe evidence which, whilst not going to the question of whether the defendant is guilty, is necessary for the jury to have a proper understanding of other evidence being given in the case by putting it in its proper context. An example might be a case involving the abuse by one person of another over a long period of time. For the jury to understand properly the victim’s account of the offending and why they did not seek help from, for example, a parent or other guardian, it might be necessary for evidence to be given of a wider pattern of abuse involving that other person.
361.For evidence to be admissible as “important explanatory evidence”, it must be such that, without it, the magistrates or jury would find it impossible or difficult to understand other evidence in the case – Section 100(2). If, therefore, the facts or account to which the bad character evidence relates are largely understandable without this additional explanation, then the evidence should not be admitted. The explanation must also give the court some substantial assistance in understanding the case as a whole. In other words, it will not be enough for the evidence to assist the court to understand some trivial piece of evidence.
362.Evidence is of probative value to a matter in issue where it helps to prove that issue one way or the other. In respect of non-defendants, evidence of bad character is most likely to be probative where a question is raised about the credibility of a witness (as this is likely to affect the court’s assessment of the issue on which the witness is giving evidence). The evidence might, however be probative in other ways. One example would be to support a suggestion by the defendant that another person was responsible for the offence.
363.Evidence which is of probative value is admissible if it meets an “enhanced relevance” test – Section 100(1)(b). That is, it must be of substantial probative value and the matter in issue to which it relates must be of substantial importance in the context of the case. Thus evidence which has no real significance to an issue or is only marginally relevant would not be admissible, nor would evidence that goes only to a trivial or minor issue in the case.
364.Section 100(3) directs the court to take into account a number of factors when assessing the probative value of evidence of a non-defendant’s bad character. These include the nature and number of the events to which it relates and when those events occurred. When considering evidence that is probative because of its similarity with evidence in the case (for example, to suggest that the alleged victim had acted in a particular way), the court is directed by subsection (3)(c) to consider the nature and extent of the similarities and dissimilarities. Similarly, where the evidence is being tendered to suggest a particular person was responsible, subsection (3)(d) requires the court to consider the extent to which the evidence shows or tends to show that the same person was responsible each time.