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Sexual Offences Against Adults

Sexual offences in Western Australia are contained in the Criminal Code Compilation Act 1913. The legislation contains a range of sexual offences against children who are too young to validly consent to sex as well as sexual offences against adults. The lack of consent is an essential element in most sexual offences against adults, 


The definition of consent is contained in Section 319 of the act and is ‘free and voluntary agreement’. A person’s consent is taken not to be free and voluntary if it was obtained through force, threats, intimidation, fraud or deceit. Section 319 specifies that a person is not to be taken to have consented to sex simply because they do not offer physical resistance. It also specifies that a child below the age of 13 cannot consent to a sexual act.

In Western Australia a person can legally consent to sex at 16 in most situations. However, where a young person is under another person’s care, they must be 18 to validly consent to sex with that person. Sexual offences that consist of having sexual contact with a child between the ages of 13 and 16 can be validly defended by adducing evidence that the child consented to the sexual act if the accused was not more than three years older than the child at the time of the alleged offence.

Sexual offences involving penetration

Sexual penetration without consent is an offence that carries a maximum penalty of 14 years imprisonment (Section 325).

Sexual penetration includes penetration of a vagina, anus or mouth by a penis or the penetration of a vagina or anus by another body part or by an object manipulated by another person. It also includes fellatio and cunnilingus. (Section 319).

If sexual penetration without consent occurs in circumstances of aggravation, a maximum penalty of 20 years imprisonment applies. Section 319 provides that circumstances of aggravation are:

  • The accused is or pretends to be armed with a weapon;
  • The accused is in the company of one or more other persons;
  • The accused does bodily harm to another person;
  • The accused acts in a way that substantially degrades or humiliates the victim;
  • The accused makes threats to kill the victim;
  • The victim is under 16 years of age.

Indecent assault

Indecent assault attracts a maximum penalty of imprisonment for five years (Section 323). An assault is indecent if the offender touches the breasts, genitals or anus of another person or if the assault was committed in indecent circumstances.

Mistaken belief in consent

If a person accused of sexual offences under Section 325, 323 or 327 held an honest and reasonable belief that the alleged victim was consenting, they can argue the defence of Mistake of Fact (Section 24). For this defence to succeed, the mistaken belief must have been based on reasonable grounds.

Sexual coercion

Under Section 327, it is an offence to coerce a person to take part in sexual behaviour. This offence carries a maximum of 14 years imprisonment. Coerced sexual behaviour may involve forcing a person to have sex with another person, forcing a person to masturbate or forcing a person to have sexual contact with an animal.

If the offence is committed in circumstances of aggravation, upon conviction, the offender will be liable to a term of imprisonment of 20 years.


It is an offence under Section 329 to engage in sexual penetration with a person who the accused knows is their lineal relative. This includes parents, siblings, half-siblings, children, grandchildren and grandparents. It also includes adoptive relationships.

Sexual offences against incapable persons

A suite of offences also exists under Western Australian law relating to sexual behaviour with incapable persons. An incapable person is a person who is mentally impaired to the point of being incapable of understanding the nature of the act or of guarding themself against sexual exploitation (Section 330).

It is an offence to sexually penetrate an incapable person knowing them to be an incapable person or to procure, incite or encourage an incapable person to sexual behaviour. It is an offence to indecently deal with an incapable person knowing them to be incapable or to procure, incite or encourage an incapable person to do an indecent act, or to indecently record such a person.

It is a defence to any of the above sexual offences if the accused was married to the incapable person at the time.

Sexual servitude

It is an offence to conduct a business involving another person being compelled to provide sexual services (Section 331C). This offence attracts a maximum penalty of 14 years imprisonment. If the alleged victim is a child or an incapable person, the maximum penalty is 20 years imprisonment.

It is an offence to offer someone employment knowing that the employment will involve giving commercial sexual services without disclosing this to the person. This offence carries a maximum penalty of imprisonment for seven years where the victim is an adult and 20 years where they are a juvenile or an incapable person.

If you need legal advice or representation in relation to sexual offences against adults or in any other legal matter please contact Armstrong Legal. 

Fernanda Dahlstrom

This article was written by Fernanda Dahlstrom

Fernanda Dahlstrom has a Bachelor of Laws, a Bachelor of Arts and a Graduate Diploma in Legal Practice. She has also completed a Master’s in Writing and Literature. Fernanda practised law for eight years, working in criminal defence, child protection and domestic violence law in the Northern Territory and in family law in Queensland.

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