The Marriage Act provides that a relevant marriage (one celebrated after 20 June 1977) is void in five circumstances, “and not otherwise”. Those circumstances are:
- the prior existing marriage of a spouse;
- prohibited relationships (marriage with an ancestor or descendent or between siblings – including adopted siblings);
- non-compliance with formalities (where the celebrant is not authorised and both parties are aware or the ceremony does not comply with prescribed form – the form adopted by a particular religion or the minimal non-religious form);
- lack of real consent of a spouse; or
- lack of marriageable age.
Additionally, the definition of “marriage” inserted into the Marriage Act in 2004 includes “the union of a man and a woman” and indicates the requirement that the parties must be respectively male and female (see also Re Kevin; Validity of Marriage 2000 28 Fam LR 158).