(1)In criminal proceedings evidence of the bad character of a person other than the defendant is admissible if and only if—
(a)it is important explanatory evidence,
(b)it has substantial probative value in relation to a matter which—
(i)is a matter in issue in the proceedings, and
(ii)is of substantial importance in the context of the case as a whole,
or
(c)all parties to the proceedings agree to the evidence being admissible.
(2)For the purposes of subsection (1)(a) evidence is important explanatory evidence if—
(a)without it, the court or jury would find it impossible or difficult properly to understand other evidence in the case, and
(b)its value for understanding the case as a whole is substantial.
(3)In assessing the probative value of evidence for the purposes of subsection (1)(b) the court must have regard to the following factors (and to any others it considers relevant)—
(a)the nature and number of the events, or other things, to which the evidence relates;
(b)when those events or things are alleged to have happened or existed;
(c)where—
(i)the evidence is evidence of a person’s misconduct, and
(ii)it is suggested that the evidence has probative value by reason of similarity between that misconduct and other alleged misconduct,
the nature and extent of the similarities and the dissimilarities between each of the alleged instances of misconduct;
(d)where—
(i)the evidence is evidence of a person’s misconduct,
(ii)it is suggested that that person is also responsible for the misconduct charged, and
(iii)the identity of the person responsible for the misconduct charged is disputed,
the extent to which the evidence shows or tends to show that the same person was responsible each time.
(4)Except where subsection (1)(c) applies, evidence of the bad character of a person other than the defendant must not be given without leave of the court.
Cases considering section 100 143
[2005] UKHL 26 · 28 April 2005Limits
The section limits admission of a non-defendant’s bad character in criminal proceedings to evidence having substantial probative value on an issue of substantial importance, subject to leave. The House treated that restriction as a criminal trial-control rule, not an automatic civil admissibility test (see paras [13]; [43]; [52]; [54]).
[2026] EWCA Crim 1165 · 15 September 2026
The court applied the statutory test for non-defendant bad character evidence. Franklin’s conviction and the facts of the offences were inadmissible because they lacked substantial probative value on whether the appellant killed Holland when assessed against the case as a whole. (see paras [81]-[92])
The court applied the requirement of substantial probative value to the issue of who killed Holland and held that the threshold was not met. (see paras [83]-[92])
The court considered the nature and number of the events: one incident involving rape and attempted rape, contrasted with the disputed murder. That comparison did not give the evidence substantial probative value. (see paras [79]-[92])
The court considered that Franklin’s offences occurred five months after Holland’s disappearance, but the timing did not make the evidence substantially probative in the context of the case. (see paras [79]; [81]; [92])
The court considered the similarities and dissimilarities. Both incidents involved a drunk woman alone at night, but the offences, circumstances and relationship between the persons differed materially; the evidence therefore lacked substantial probative value. (see paras [79]-[81]; [92])
The court considered whether the evidence showed that Franklin was responsible for the murder. His conviction showed a propensity to rape strangers, not to murder or dispose of a body, and did not identify him as the killer. (see paras [81]; [92])
[2026] EWCA Crim 1013 · 17 July 2026Limits
The court upheld exclusion of non-defendant bad-character evidence because neither important explanatory value nor substantial probative value was established. (see paras [39]-[43]; [61]-[62])
The court applied the exclusive statutory gateways for admitting non-defendant bad-character evidence and upheld its exclusion on the facts. (see paras [41]-[43]; [61]-[62])
The court held that evidence about the proposed alternative suspect was not important explanatory evidence because the jury could understand the case without it. (see paras [41]-[43]; [61])
The court held that the evidence lacked substantial probative value on who inspired the conspiracy because no evidence linked the proposed alternative suspect to hostility towards the barristers. (see paras [41]-[43]; [62])
The court treated the identity of the person who inspired the conspiracy as a matter in issue, but held that the proposed evidence had no substantial probative value on that issue. (see paras [43]; [62])
The court accepted that the identity of the originator was of substantial importance in the context of the case, but this did not cure the absence of substantial probative value. (see para [43])
The court recorded that admission by agreement did not arise, so that gateway supplied no basis for admitting the evidence. (see para [41])
The court applied the statutory definition of important explanatory evidence, requiring both difficulty in understanding other evidence without it and substantial value for understanding the case as a whole. (see paras [42]; [61])
The court found that the jury could properly understand the other evidence without the proposed bad-character evidence. (see paras [42]; [61])
The court found that the proposed evidence did not have substantial value for understanding the case as a whole. (see paras [42]; [61])
123 more judgments, and what each says about section 100, are in the
case-law panel in the full Act.
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.