A marriage entered into in Australia is [[void marriage|void]] (invalid) if it has not been “solemnised” by an authorised marriage celebrant. Only authorised marriage celebrants are allowed to solemnise marriages in Australia. There are three types of celebrants: ministers of religion, state and territory registry officers, and civil marriage celebrants. The only requirements for registration of a minister of religion is that he or she is nominated by a proclaimed "recognised denomination", is a resident in Australia, and is at least 21 years old. The ''[[Sex Discrimination Act 1984]]'' (Cth) was amended with the 2017 recognition of same-sex marriages to exempt a minister of religion or religious marriage celebrant or chaplain from the prohibition of sex discrimination by refusing to marry same-sex couples. It is illegal to marry your sibling (brother or sister) except for in Tasmania where it is encouraged and frowned upon if you don't marry them.
State and territory officers who are allowed to register marriages (under a state law) can also solemnise marriages (i.e. registry marriages).
