Last reviewed: 25 May 2026
Incest is a criminal offence in NSW because the law recognises that sexual relationships between close family members can involve serious issues of trust, dependence, vulnerability and harm. The offence is not treated as a private relationship issue, even where both people appear to consent.
In NSW, incest is dealt with under the Crimes Act 1900. The law applies to sexual intercourse between close family members and includes specific provisions for attempted incest, available defences and prosecution approval requirements. The Crimes Act 1900 is the main criminal statute setting out many offences and penalties in NSW.
The key point is this: consent is not a defence to incest in NSW. A person may still be charged if the legal elements of the offence are made out.
Quick Answer: Why Is Incest A Crime?
Incest is a crime because the law treats sexual activity between close family members as a serious public concern. The offence is designed to address the risks that can arise within family relationships, including abuse of trust, emotional pressure, power imbalance and harm to family boundaries.
The law does not only focus on whether both people agreed. It also considers the prohibited family relationship and the broader concern that close family sexual relationships can involve vulnerability, coercion or exploitation.
What Is Incest Under NSW Law?
Incest generally refers to sexual intercourse between close family members. In NSW, the offence applies where a person has sexual intercourse with a close family member who is 16 years or older.
A close family member may include:
- a parent
- a child
- a sibling
- a half sibling
- a grandparent
- a grandchild
The relationship may be by birth or through another legally recognised family relationship. In some cases, whether the accused person knew about the family relationship may become an important legal issue.
For related sexual offence matters, see KPT Legal’s page on sexual offences in NSW.
Incest Laws In NSW: Key Points
| Issue | What It Means |
| Main offence | Sexual intercourse with a close family member |
| Age requirement | The other person is 16 years or older |
| Consent | Consent is not a defence |
| Attempt | Attempted incest is also an offence |
| Possible defence | The accused did not know of the family relationship |
| Prosecution approval | Attorney General approval is required |
| Maximum penalty | Incest can carry up to 8 years imprisonment |
| Related offences | Sexual assault, sexual touching and child sexual offences may also be relevant |
This table gives a quick summary, but the outcome of any case depends on the exact charge, the evidence and the surrounding circumstances.
Why Is Incest Treated As A Criminal Matter?
Incest is treated as a criminal matter because close family relationships often involve emotional, psychological and social complexities that are different from ordinary adult relationships.
Family relationships can involve trust, dependence, authority and long-term influence. Even where both people are adults, the law recognises that these dynamics can create a risk of exploitation or harm.
The criminalisation of incest reflects concerns about:
- abuse of trust within a family
- vulnerability or dependence
- emotional and psychological harm
- power imbalance
- family disruption
- public interest in protecting family relationships
This is why NSW law does not treat incest as a simple question of personal consent.
What Counts As Sexual Intercourse?
Sexual intercourse has a broad legal meaning in NSW. It is not limited to one form of sexual activity.
It can include penetration, oral sex and the continuation of those acts. Conduct performed for a proper medical purpose is treated differently.
Because the definition is broad, a person should not assume that an allegation falls outside the law without legal advice. The exact conduct alleged and the evidence available will matter.
Who Counts As A Close Family Member?
Close family relationships can include direct family relationships and sibling relationships.
Common examples include parent and child, grandparent and grandchild, siblings and half siblings. In some cases, the legal issue may be whether the accused knew of the family relationship.
This may become relevant where people:
- were separated at birth
- were adopted into different families
- did not grow up together
- were not told about the family connection
- reasonably believed they were unrelated
If the family relationship is disputed, evidence about family history, records, communications and personal knowledge may become important.
Is Consent A Defence To Incest?
No. Consent is not a defence to incest in NSW.
This is one of the most important differences between incest and many other sexual offence allegations. In many sexual offence cases, whether a person consented can be a central issue. In an incest charge, the law focuses on the prohibited family relationship and the sexual conduct.
This means a person may still be charged even if both people appeared to agree.
What If The Accused Did Not Know They Were Related?
A possible defence may arise where the accused person did not know the other person was a close family member.
This type of defence may be relevant in unusual cases, such as where people were separated, adopted, raised apart or otherwise unaware of the family relationship.
However, whether this defence can be raised depends on the evidence. A lawyer would need to assess what the accused person knew, what they were told and whether the prosecution can disprove the defence.
Attempted Incest In NSW
Attempted incest is also a criminal offence.
An attempted offence may arise where police allege that a person took steps towards committing incest, even if sexual intercourse did not occur.
Attempt cases can be legally complex because the prosecution may need to prove both intention and conduct sufficiently connected to the alleged offence. Communications, witness evidence and surrounding circumstances may all become relevant.
Why Does The Attorney General Need To Approve A Prosecution?
In NSW, a prosecution for incest or attempted incest requires approval from the Attorney General.
This requirement reflects the seriousness and sensitivity of these allegations. It does not mean a case cannot proceed. It means there is an additional approval step before prosecution.
Because this is a procedural requirement, it may be important for a lawyer to check whether the prosecution has complied with the necessary process.
Incest Charges And Other Sexual Offences
Incest allegations may overlap with other sexual offences depending on the facts.
A matter may involve separate or alternative allegations such as:
- sexual assault
- sexual intercourse without consent
- sexual touching
- child sexual offences
- historical sexual offences
For example, if the allegation involves lack of consent, a complainant under 16, coercion or abuse of authority, the legal issues may extend beyond the incest provisions.
Penalties For Incest In NSW
Incest is a serious offence and can carry a maximum penalty of up to 8 years imprisonment.
The sentence in a particular case will depend on the facts, including:
- the relationship between the people involved
- whether there was abuse of trust
- whether there was vulnerability or dependence
- whether the conduct was repeated
- whether the accused pleaded guilty
- the accused person’s criminal history
- the impact on the other person
- prospects of rehabilitation
Possible outcomes may include a non-custodial sentence, an Intensive Correction Order or full-time imprisonment, depending on the seriousness of the case.
Can An Incest Charge Lead To Prison?
Yes. Incest can lead to imprisonment.
A court will consider the seriousness of the conduct, the family relationship, any abuse of trust and the personal circumstances of the accused. The outcome cannot be assumed simply because both people were adults or because consent is alleged.
If a person is charged with incest, early legal advice is important because the case may involve complex evidence, family history, sensitive allegations and serious penalties.
Why These Cases Are Sensitive
Incest cases are often highly sensitive because they involve family relationships, sexual allegations and private history. They can also affect more than the criminal proceedings.
A case may involve family conflict, disputed memories, historical allegations, reputational harm, mental health concerns or contact between multiple family members who may become witnesses.
For this reason, legal advice should be careful, discreet and strategic.
What If The Allegation Is Historical?
Some incest allegations relate to events said to have happened many years earlier.
Historical cases can be complex because they may involve limited physical evidence, old records, memory issues and competing accounts. A delay in reporting does not automatically mean the allegation will fail, but it may affect how the evidence is tested.
Evidence in a historical case may include:
- family records
- earlier disclosures
- messages or letters
- witness accounts
- counselling or medical records
- prior complaint evidence
- surrounding family circumstances
Anyone facing a historical allegation should get legal advice before speaking to police or family members about the matter.
What Should You Do If Police Contact You?
If police contact you about an incest allegation, get legal advice before attending an interview or making a statement.
You should avoid contacting the complainant, avoid discussing the allegation online and keep any relevant records. Anything said to police, family members or witnesses may later become evidence.
KPT Legal’s guide on what not to say in a police statement may be useful if police want to speak with you.
Possible Defences To Incest Charges
The available defence depends on the charge and the evidence.
Possible legal issues may include:
- the accused did not know the other person was a close family member
- the prosecution cannot prove the family relationship
- the prosecution cannot prove sexual intercourse
- mistaken identity
- unreliable or inconsistent evidence
- insufficient evidence
- procedural issues with prosecution approval
Consent is not a defence, so the defence strategy usually needs to focus on other legal elements of the charge.
How A Criminal Defence Lawyer Can Help
A criminal defence lawyer can assist by reviewing the charge, advising before a police interview, checking the evidence and explaining the available legal options.
In incest cases, legal assistance may include:
- assessing whether the family relationship can be proved
- checking whether the Attorney General approval requirement has been met
- reviewing police evidence and witness statements
- advising on possible defences
- preparing for court
- advising on plea options
- preparing sentencing material if required
Because incest charges are serious and sensitive, early legal advice can help reduce uncertainty and protect the accused person’s rights.
Speak To KPT Legal About Incest Charges
Incest allegations can have serious legal, personal and reputational consequences. If you have been contacted by police, charged with incest or accused of a related sexual offence, it is important to get legal advice before making decisions.
The team at KPT Legal provides clear advice and representation for people facing serious criminal allegations in NSW. KPT Legal can help you understand the charge, review the evidence, respond to police and prepare your next steps.
FAQs About Incest Laws In NSW
Why Is Incest A Crime In NSW?
Incest is a crime because the law recognises the risks that may arise in close family sexual relationships, including abuse of trust, emotional harm, vulnerability and public interest concerns.
Is Consent A Defence To Incest?
No. Consent is not a defence to incest in NSW. A person can still be charged even if both people appeared to agree.
What Is The Maximum Penalty For Incest?
Incest can carry a maximum penalty of up to 8 years imprisonment, depending on the offence and circumstances.
Is Attempted Incest A Crime?
Yes. Attempted incest is also a criminal offence in NSW.
What Should I Do If Police Want To Interview Me?
You should get legal advice before speaking to police. Anything said in an interview may later be used as evidence.
Final Thoughts
So, why is incest a crime? In NSW, incest is criminalised because the law treats close family sexual relationships as a serious concern involving trust, family boundaries, vulnerability and public interest.
Incest charges can involve complex legal and personal issues, including family history, disputed evidence, statutory defences and serious sentencing risks. Because consent is not a defence, it is important to understand what legal issues are actually available in the case.
If you are facing an incest allegation or a related sexual offence, get legal advice early. The decisions made before a police interview or first court date can affect the direction of the case. Contact KPT Legal for confidential advice about incest charges, sexual offence allegations and criminal defence options in NSW.
Disclaimer: The above content is for general informational purposes only and should not be regarded as legal advice. The information provided may change over time. You should always seek professional advice before taking any action.
