I am not sure what you mean exactly by 'consummated,' however, a declaration of nullity is a finding that there was no legal marriage between the parties, even though a marriage ceremony may have taken place. A court may declare a marriage invalid on the following grounds:
one or both of the parties were already married at the time
one or both of the parties were under-age and did not have the necessary approvals, or
one or both of the parties were forced into the marriage under duress.
Under the Family Law Act 1975, the Family Court of Australia and the Family Court of Western Australia have the power to declare a marriage invalid.
To apply for nullity, you must file an Application for Final Orders. You will also need to prepare an affidavit stating:
the facts relied on to have the marriage annulled, and
details of the type of marriage ceremony performed.
If the respondent is in Australia, the Court will give a hearing date that is within 42 days of the application being made. If the respondent is not in Australia, the hearing date will be at least 56 days after the application is made.
If you are the applicant, you will have to serve the papers on the respondent. More information can be found in the Family Court of Australia form 'Service Kit (Do it yourself kit)' under the Forms section of the Family Court website (www.familylawcourts.com.au)