Propensity and Relationship Evidence (WA)

By James Stevens, Director and Solicitor, Go To Court Lawyers. Last reviewed 20 April 2026.

Propensity evidence is evidence that is adduced to demonstrate that a person has a tendency to behave in a certain way. Relationship evidence is evidence that a person has a particular type of relationship towards another person or class of persons. Propensity and relationship evidence are admissible in criminal proceedings only subject to very strict rules. This page deals with evidence law as it related to propensity and relationship evidence.

Legislation

The Evidence Act 1906 defines propensity evidence as:

• similar fact evidence or evidence of the conduct of a person; or
• evidence of the character or reputation of a person or of a tendency they have or had.

It defines relationship evidence as evidence of the attitude or conduct of the accused to wards another person or class of person over time.

Section 31A of the Evidence Act 1906 states that propensity and relationship evidence is admissible if the court considers that:

• the evidence would have significant probative value
• the probative value, compared with the risk of an unfair trial, is such that a fair-minded person would think that the public interest in adducing the evidence should be given priority over the risk of an unfair trial.  

Probative value

The probative value of evidence is the usefulness of the material in establishing facts that are in dispute. Evidence will be found to have probative value if, either on its own or in combination with other evidence before the court, it is of importance or consequence.

In assessing whether evidence has probative value, the court must consider the extent to which evidence of a person’s past behaviour can affect the assessment of whether they committed the offence with which they are presently charged.

In making this assessment the court must not consider the possibility that the evidence is the result of collusion, concoction or suggestion.

Prejudicial effect

Propensity and character evidence can also be highly prejudicial in a criminal proceeding. This is because jurors may over-estimate the weight that should be given to such evidence, may form a bias against the accused, or may reason that because the accused committed other similar acts, that they must have committed the offence charged. Because of the potential for propensity evident to prejudice a trial, such evidence must only be admitted where this is in the public interest.

The State of Western Australia v Edwards [2019] WASC 87

In the 2009 decision of Edwards (the Clairemont serial killer case), the prosecution applied to have evidence of the accused’s conduct in relation to some of the charges (if proven) admitted as evidence in relation to other charges as propensity evidence. The prosecution also sought to adduce evidence of various other acts by the accused, including both charged and uncharged acts.

The prosecution made this application in order to establish that the accused had a propensity to prowl a particular area at night to seize opportunities to commit sexual offences.  

It argued that the evidence had a high degree of probative value due to the common features between all of the acts and demonstrated an underlying unity that assisted in establishing the identity of the offender, which was the key issue.

The court found that the propensity evidence was admissible in relation to one set of charges as all the acts related to the same geographic area, were close in time and were connected by the wearing or possession of a kimono. However, the evidence was not admitted in relation to other charges on the indictment that were alleged to have occurred outside of that geographical area.  

Conclusion

In summary, the likelihood the relationship or propensity evidence will be admitted into a criminal proceeding depends on its probative value and whether it is in the public interest to admit the evidence taking into account its potential to prejudice the trial. This will be assessed with regard to all the circumstances, including the seriousness of the offending, the proximity of the relationship between different incidents and the value of the evidence in establishing key issues that are in dispute.

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