A transparency advocate has begun his latest bid to have key documents in the implementation of the robodebt scheme made public.
Justin Warren was in the Federal Court on Wednesday where he is appealing a previous decision to block the release of documents about the business case behind the illegal welfare scheme.
The 11 documents he's seeking could reveal what prominent coalition government ministers like Scott Morrison and Christian Porter knew about the scheme.
Services Australia remains opposed to the release, having won at the Administrative Appeals Tribunal in December 2022 before Mr Warren launched his appeal.
Speaking at a break in court proceedings, Mr Warren said his case was designed to highlight the importance of timely information being provided so things like robodebt cannot happen again.
"This case demonstrates the importance of timely access to information about government decision-making so that when this kind of egregious error is made, the public discovers it early so it can be quickly corrected or stopped," he told AAP.
"It has now been almost seven years since I first made the request ... I never imagined it would take this long, nor did I imagine that robodebt would turn into one of the greatest administrative failures in Australian history."
His lawyers are arguing his AAT hearing was procedurally unfair, and their submissions about the public interest in the documents were interpreted with legal error.
They also argued the evidence put forward by Services Australia in written submissions was changed, but they were not informed about it.
"There are a lot of questions I could have asked had I known I was making the case I now know was being run," his lawyer told the court.
"(There was) simply no indication that was the case being run."
The robodebt scheme, initiated under the former coalition government in 2015, sought to recover $1.2 billion over four years from more than 860,000 welfare recipients.
But more than $750 million was wrongfully recovered from 381,000 people.
The federal government is implementing 56 recommendations from a royal commission into the scheme.
But it won't take up a suggestion that cabinet documents should not automatically be made confidential, rather only when there is a justifiable public interest reason.
Government Services Minister Bill Shorten said respect for cabinet confidentiality was an important principle.
"While we appreciate the royal commissioner's suggestion, we weren't convinced of that," he told reporters in Canberra.
"The other 56 things we're doing we've accepted fully or accepted in principle or implemented."
The inquiry's commissioner Catherine Holmes referred individuals for civil action and criminal prosecution, and the Australian Public Service Commission is investigating 16 involved with the scheme.
The court hearing continues.
