Former sports minister Bridget McKenzie could be personally liable for failing to seek advice about whether she had the legal authority to give out $100m of sports grants, a senior academic has told a Senate committee.

On Tuesday Geoffrey Lindell, emeritus professor in law at the University of Adelaide, said he had “serious doubts” that McKenzie had authority to approve the grants, echoing concerns of the Australian National Audit Office and other experts including professor Anne Twomey.

Lindell told the Senate committee on the administration of sports grants in Adelaide that the same “cloud” hung over whoever made late changes to the final round of grants on 11 April, which McKenzie has said she was unaware of.

The guidelines for the community sport infrastructure grant program said the minister was the final decision-maker, but Lindell told the Senate inquiry into sports grants he had searched in good faith for the source of that authority and was “yet to find it”.

Lindell noted that the attorney-general has defended McKenzie’s conduct by arguing a minister’s discretion to direct their department, but responded that Sport Australia was an independent statutory authority, not a department.

“Despite what the attorney said, I find myself in disagreement,” he told the hearing.

Lindell noted that Sport Australia had a power of delegation, but the minister was not listed as a possible delegate, and the minister had a power to set “practices and policies” but that did not allow her to supplant Sport Australia as the decision-maker.

Lindell noted several law firms have threatened to bring legal challenges, suggesting that if they succeeded the minister’s decisions would have “no legal effect” and Sport Australia would have to decide grants afresh.

Maurice Blackburn has written to Sport Australia on behalf of the Beechworth Lawn Tennis Club, an unsuccessful applicant, asking that it approve its grant application by 17 March or face legal action in the federal court.

Lindell said legal actions would take their course but “wherever possible I would’ve thought the right thing to do would be to fund the very deserving [projects] that missed out”.

In his submission, Lindell noted that the Public Governance Performance and Accountability Act could allow the commonwealth to recover grant money from McKenzie for “loss of relevant money”.

“For this liability to be established it would have to be shown that the payments resulted from her ‘misconduct or by a deliberate or serious disregard of reasonable standards of care’,” he submitted.

At the hearing, Lindell said he did not elaborate on the point because, given the amount of money involved, he could not “think of anyone pursuing that”.

“There are also little explored possible criminal consequences when public officers don’t comply with statute law, particularly when done with full knowledge of the facts,” he said.

Lindell suggested McKenzie should be censured by parliament for failing to check if she had legal authority to give grants, or else her staff should be held responsible, or else a “vacuum” of responsibility would develop.

Liberal senator Eric Abetz suggested censure of McKenzie would be inappropriate because she was not aware she may have lacked legal authority to give grants.

McKenzie and the prime minister, Scott Morrison, have repeatedly defended the program on the basis that Sport Australia assessed all projects ultimately funded as eligible under the guidelines.

On Thursday McKenzie reignited the sports rorts controversy by insisting she made no changes to the brief and attachments outlining successful projects funded under the sports grants scheme after 4 April 2019.

In a statement on her website – the first public intervention since stepping down from the ministry – McKenzie said: “I did not make any changes or annotations to this brief or its attachments after 4 April 2019.

“My expectation was that the brief would be processed in a timely and appropriate manner. Nevertheless, changes were made and administrative errors occurred in processing the brief.”

Asked about how the late changes might affect the legality of the program, Lindell said the “position doesn’t change”.

“What I say about the minister lacking authority to direct decisions or be the effective decision-maker … applies equally and perhaps even more strongly to a mere offical in the minister’s office, the prime minister’s office or the prime minister himself,” he said. “The cloud hangs over all of them.”

Lindell said his concerns about the legality of the program were shared by colleagues of “unquestioned” credibility: Anne Twomey, Michael Crommelin and Cheryl Saunders. He said the only doubt on the question was if the attorney general could “pinpoint the legal authority” that they had overlooked.

Earlier, the committee heard from South Australian clubs that scored above the 74% cutoff that the audit office found would have resulted in a grant if Sport Australia’s advice had been followed, including the Coromandel Valley Ramblers Cricket Club, with a score of 90, and McLaren Football Club, with a score of 88.

Witnesses from clubs told the committee they had spent up to 400 hours completing applications for a process they believed was merit-based, but received no feedback from Sport Australia about why they were unsuccessful.