Generally, Australian records more than 30 years old are accessible to the public. This applies to all states and territories with some variation as to form of access. For example, in the NT one would apply for access under the FoI Act, yet under this process one might access virtually any kind of records up to today. In most instances records have to be accessed physically in reading rooms under rather strict conditions. However, some states will even hand-deliver records to you.
See also tracing family