Last updated 27 April 2022

Section 51 of the Family Law Act 1975 (Cth) (Family Law Act) provides that an application for a decree of nullity of marriage shall be based on the ground that the marriage is void.

The effect of a nullity decree is to declare that, because of certain facts surrounding the purported marriage, it has never been a true marriage.

The grounds for finding that a marriage is void are:

  • bigamy—either of the parties was at the time of the marriage lawfully married to another person
  • the parties are within a prohibited relationship (see above)
  • invalid ceremony—a failure to comply with the laws regulating marriage ceremonies in the country where the marriage took place
  • lack of real consent—both parties did not give their real consent to it. Consent may not be real because of fraud, duress, mistake or mental incapacity
  • marriageable age—either party was not of marriageable age.

For a person involved in a void marriage, it is not sufficient to simply say the marriage does not exist. An application for a decree of nullity must be made to the Federal Circuit and Family Court of Australia. A copy of the application must be served on the other party to the marriage. At the court hearing, the judicial officer will hear evidence as to why the marriage is void. If the court is satisfied that the marriage is void, a decree of nullity will be issued. The effect of that decree is to declare that the marriage never existed.