The DIBP’s failure to register a legislative instrument in more or less the same manner as it failed to do in the cases of Singh v. Minister for immigration & Anor  FMCA 145 and Sharma v. Minister for Immigration and Multicultural Affairs & Citizenship  FCCA 2821 could effectively invalidate applications lodged between October 1999 and 16 March 2016.
The DIBP’s failure to in effect record all of its Forms as “Approved Forms” via the mechanism of a legislative instrument in the said period could potentially raise legal issues.
That being the case, if Schedule 1 requires an applicant to lodge an application on an approved form, then absent any approved form during the relevant period, that defect would render the application invalid.
This could be useful to applicants who have been refused a visa between October 1999 and 16 March 2016, and considering the implications of the operations of secs 48 and 48B of the Migration Act 1958.
Source: Christopher Levingston news article available at: https://migrationalliance.com.au/immigration-daily-news/entry/2016-07-it-is-a-miracle.html