Documents that may have revealed what former ministers knew about the failed robodebt scheme will not be released, a tribunal has ruled.
Advocate Justin Warren first requested access to the 12 documents in 2017 under freedom of information laws but the Administrative Appeals Tribunal on Sunday decided to only release one.
The requested documents include early business plans produced by the Department of Human Services, now known as Services Australia, to justify the robodebt scheme.
Mr Warren believes the full set of documents could reveal what former Prime Minister Scott Morrison and senior ministers including Christian Porter and Alan Tudge knew about the scheme.
"We deserve to know everything about how this happened so we can ensure that it never ever happens again," Mr Warren said in a statement on Sunday.
"Until we know the truth, the whole truth, of how this abhorrent scheme was proposed, built and sanctioned - and by whom - we have to assume the government intends to do it again."
Maurice Blackburn Lawyers, which is running the case as part of the Grata FOI Project, will consider options to appeal the tribunal's decision.
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.
A royal commission into robodebt is now underway with public hearings continuing in Brisbane on Monday.
Former Prime Minister Scott Morrison is expected to front the commission on December 14.
