Last updated 27 April 2022
The Marriage Act 1961 (Cth) (Marriage Act) provides that a person may marry if they are:
- unmarried at the time of the marriage ceremony
- of marriageable age
- not marrying a person in a prohibited relationship
- able to freely consent to the marriage.
Persons already married
A marriage is void (i.e. legally the marriage never occurred) if one or both parties are, at the time of the marriage, already legally married to someone else (s 23 Marriage Act). This is called ‘bigamy’, which is an offence punishable by up to seven years imprisonment (s 360 Criminal Code Act 1899 (Qld)). If a bigamous marriage has occurred, one or both of the parties may apply to the court for a decree of nullity, which legally declares that the marriage is void.
Polygamous marriages (i.e. marriages where a person has more than one husband or one wife) are not valid in Australia. However, polygamous marriages are recognised if they occurred outside Australia (e.g. in Islamic countries) (s 6 Family Law Act 1975 (Cth)).
Under the Marriage Act, a person can marry at 18 years of age (s 11 Marriage Act).
A person over 16 but under 18 years of age can marry, but only with the consent of their parent(s), a relevant person, or a judge or magistrate (ss 12, 13 Marriage Act). If a child needs to obtain parental consent, the following applies:
- When both parents are alive, consent should be obtained from both parents.
- If the parents are living separately, and there is a court order in force granting one or more persons parental responsibility, the child must obtain the consent of each person under the order with parental responsibility.
- If the child does not live with either parent and the parents have never been married, the consent of the mother is required.
- If either or both parents are dead, both parents have been deprived of the care of the child by a court order or the child is adopted, the consent is required from the child’s appointed guardian(s) or the people listed in the sch 1 of the Marriage Act.
The consent must be written, witnessed and presented to the person celebrating the marriage not earlier than three months before the marriage ceremony (s 13 Marriage Act).
If the parent refuses to give consent, the child may apply to a judge or magistrate for consent (s 16 Marriage Act). A magistrate or judge can only provide consent if the other proposed spouse is over 18 years (s 12(1) Marriage Act).
A marriage involving a person under 18 years where parental and court consent has not been obtained is void (s 23B(1)(e) Marriage Act). A person who goes through a marriage ceremony without that consent may be guilty of an offence punishable by up to five years imprisonment (s 95(1) Marriage Act).
A marriage will not be valid if the parties are in a ‘prohibited relationship’ (s 23B(1)(b) Marriage Act). A prohibited relationship is one between a brother and sister (including half-blood) or between a person and an ancestor (i.e. a parent or grandparent) or descendant (i.e. a child or grandchild). For an adopted child, these rules apply to their adopted family as well as their natural family. It is not unlawful for cousins to marry one another. A marriage between parties in a prohibited relationship is void.
A marriage must be entered into freely and consensually. A marriage will be void where:
- there is fraud or duress
- there is a mistake by one or both parties about the identity of either party or the nature of the marriage ceremony
- one of the parties is mentally incapable of understanding the nature and effect of the marriage ceremony (s 23B(1)(d)(iii) Marriage Act).
Transsexual persons can validly enter into marriage. In the landmark case of Re Kevin: Validity of Marriage of a Transsexual  FamCA 1074, the court established that the meaning of the word ‘man’ in the Marriage Act may include a post-operative female-to-male transsexual person. It also established that whether or not a person is a man or a woman is determined at the date of marriage and not at birth.
Same-sex marriages are recognised as valid marriages in Australia since 9 December 2017 with the passing of the Marriage Amendment (Definition and Religious Freedoms) Act 2017 (Cth). These amendments provide equal marriage laws to two adults, irrespective of gender.
Overseas same-sex marriages solemnised on or before 9 December 2017 are automatically recognised in Australia with the amended definition of marriage.