PROPENSITY, TENDENCY AND SIMILAR FACT EVIDENCE

Propensity, tendency and similar fact evidence
a) Propensity evidence: this establishes that there is a certain way in which the person habitually acts.

b) Tendency evidence: this is related to the likelihood of someone acting in a specific way.

c) Similar fact evidence: factually the situations of the alleged wrongdoing and the evidence are very similar and show guilt.

This type of evidence is dangerous because it is not very reliable and it is difficult for the trier of fact to know how much weight to give to it. It is excluded unless it can be shown to be reliable. Alternatively it may be used with a warning or if it is corroborated.

Common law
Generally propensity evidence is not permitted. Instead character can be assessed through credit by cross-examination (see COURSE OF THE TRIAL). Where due to a propensity or tendency of the accused to act or think in other occasions in a particular way it is suggested or inferred that in the situation in question they acted in the same way then the evidence is excluded. It will be allowed only where it is very relevant and goes towards establishing one of the facts in issue ("high probative force"). Unless there is no rational view of the evidence which is consistent with the accused’s innocence it will have to be withdrawn. Uncharged criminal acts and non-criminal misconduct are considered part of propensity evidence.

Similar fact evidence is also subject to exclusion unless there is exceptional probative value. However where the accused seeks to adduce such evidence then it simply has to be relevant. It is for the jury to determine the credibility of the propensity evidence.

Evidence going to relationships has a more limited role. For example this may be evidence of the victim and the accused’s relationship. Relationship evidence may be used for other purposes but propensity may be raised incidentally. If so the accused must convince the court to exclude it.

Some examples of where propensity evidence is allowed are to prove that a crime was committed, to prove that the accused committed the crime, to prove the voluntariness of the act or to show the accused’s intention.

Legislation
In Western Australia there are certain situations in which propensity or relationship evidence is admissible where it has ‘significant probative value’ (i.e. goes towards establishing the facts in issue) or that there is public interest in allowing the evidence despite the risk of an unfair trial.