Advice to Scott Morrison at centre of five-year legal battle that cost taxpayers $400,000 finally released

A chapter has finally closed on a five-year legal battle, costing more than $400,000 of taxpayer money, over a letter of advice from the former attorney general Christian Porter to then prime minister Scott Morrison on the “sports rorts” saga.

The letter, now released to self-described “transparency warrior” Rex Patrick, and seen by Guardian Australia, states then sports minister Bridget McKenzie had authority to administer a $100m sports grants program, and it bookends a series of freedom of information requests and two court cases.

Patrick told Guardian Australia: “The whole saga has been an improper assault on government transparency and accountability, and a disgraceful waste of taxpayers’ money.”

The battle for the letter has passed through four attorneys general: from Porter, to Michaelia Cash under the Coalition, to Katy Gallagher and then to Mark Dreyfus of the ALP.

Patrick’s request for the document from the Morrison governmentwas delayed and then fell into the hands of the Albanese government, who refused his request.

He took the issue to court, and the saga became a broader legal battle over whether a minister should be able to shred their documents once leaving office.

The court found they could not, meaning ministers must retain legal responsibility for predecessors’ documents and must preserve them until any FoI process is concluded.

Patrick said the Morrison government can “claim partial success” due to the advice being released after they left office.

“The Albanese government resisted disclosure, fighting a precedent set … that prohibits ministers from shredding what they consider to be their documents after they leave office.”

The government tried to appeal that decision to a full federal court last year, which rejected the commonwealth’s attempt to keep ministerial documents beyond the reach of FoI requests after their authors leave office.

Morrison requested advice from Porter on whether McKenzie, then sports minister, had wrongly administered the Coalition government’s controversial $100m sports grants program in 2020, according to a report by the auditor general, which had blown up in the media, and ultimately saw McKenzie resign from the Coalition frontbench.

The question went to whether she had the authority to direct funds from the Australian Sports Commission, an independent commonwealth agency.

That advice from Porter will finally become public. It states McKenzie was within her remit as a minister, and member of the executive, to make some funding decisions “without specific statutory authority”.

Porter’s now-public advice differed from the opinion of constitutional legal expert Anne Twomey, who told parliament during a Senate inquiry in March 2020 into the program that McKenzie had no power under the relevant law to direct the Sports Commission to make certain funding decisions.

Twomey said unlike a department, where a minister has the authority to direct its public servants, the Australian Sports Commission was created by law as an independent corporate entity.

She asserted that McKenzie could direct the commission in exercising its powers, but could not exercise those powers herself. Twomey said any direction must be in writing, published and tabled in parliament, which she said the minister didn’t do.

In his letter, Porter wrote it would be “onerous and unnecessary” for a ministerial direction to be signed every time a minister wanted to play a role in the administration of an authority.

“[For] two and a half years,’ Patrick said, “the Morrison government resisted disclosure. It wanted to bury dodgy legal advice that was used to legitimise Senator McKenzie’s ‘sports rorts’ conduct”.