Sexual Offences Against Adults (WA)

By James Stevens, Director and Solicitor, Go To Court Lawyers. Last reviewed 15 April 2026.

Sexual offences in Western Australia are governed by the Criminal Code Compilation Act 1913. That act contains a range of sexual offences against children who are below the relevant ages of consent as well as sexual offences against adults. For most sexual offences against adults, the absence of consent is an essential element.

Consent

Consent is defined in Section 319 of the act as free and voluntary agreement. Consent is taken not to be free and voluntary if it is obtained by force, threats, intimidation, deceit or fraud. Section 319 specifies that a person is not to be taken to consent simply because they do not offer any physical resistance. It also specifies that a child under 13 cannot consent to a sexual act.

In Western Australia the age at which a person can consent to sex is generally 16. However, where a child is under a person’s care, he or she must be 18 to validly consent to sex with that person. An offence of having sexual contact with a child between the ages of 13 and 16 can be defended by evidence that the child consented to the sexual act if the person was not more than three years older than the child at the time of the sexual act.

Sexual penetration

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

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

If sexual penetration without consent is committed in circumstances of aggravation, a maximum penalty of 20 years imprisonment applies.  Circumstances of aggravation provided under Section 319 are:

• The accused is or pretends to be armed with a weapon;
• The accused is in the company of another person;
• The accused does bodily harm to another person;
• The accused acted in a way that substantially degraded or humiliated the victim;
• The accused made threats to kill the victim;
• The victim was under 16 years of age.

Indecent assault

Indecent assault carries  a maximum penalty of 5 years imprisonment (Section 323). An assault is indecent if it involves touching an indecent part of the body (breasts, genitals or anus) or if it was committed in indecent circumstances.

Mistaken belief in consent

If a person charged with an offence against Section 325, 323 or 327 held an honest and reasonable belief that the victim was consenting, the accused can argue the defence of Mistake of Fact (Section 24). To succeed as a defence, the mistaken belief must have been based on reasonable grounds.

Sexual coercion

It is an offence under Section 327 to coerce a person to engage in sexual behaviour. This offence carries a maximum of 14 years imprisonment. Examples of coerced sexual behaviour are forcing a person to have sex with another person, forcing a person to masturbate or to have carnal knowledge of an animal.

Incest

It is an offence under Section 329 to have sexual penetration with a person who the accused knows is his or her lineal relative. This includes parents, siblings, children, grandchildren and grandparents. It includes half-siblings and relationships established by adoption.

Sexual offences against incapable persons

A suite of offences also exists relating to sexual behaviour with incapable persons. An incapable person is a person who is so mentally impaired as to be incapable of understanding the nature of the act or of guarding him or her self against sexual exploitation (Section 330).

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

However, it is a defence to any of these offences if the accused was at the time of the relevant act, married to the incapable person.

Sexual servitude

It is an offence to conduct a business that involves another person being compelled to provide sexual services (Section 331C). This offence carries a maximum of 14 years imprisonment, or if the person is a child or an incapable person, 20 years imprisonment.

It is an offence to offer a person employment knowing that the employment will involve offering commercial sexual services without disclosing this knowledge to the person. This offence carries a maximum penalty of 7 years imprisonment where the victim is an adult and 20 years where the victim is a child or an incapable person.

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