An eminent legal expert believes the sports rorts program may have been administered unlawfully and suggests former sport minister Bridget McKenzie could be personally liable for funding decisions.

Emeritus law professor Geoffrey Lindell said he had "serious doubts" about whether Senator McKenzie had the power to approve grants under the program. He told a Senate committee hearing in Adelaide that she could be personally accountable under a rarely-used law.

"We can't just leave it in a vacuum," Professor Lindell said in response to questions from Liberal senator Eric Abetz suggesting Senator McKenzie was unaware of some developments in the grants process. "Someone has to be responsible for what happens in the minister's office."

The government has relied on advice from the Australian Government Solicitor commissioned by the Attorney-General to argue the grants program was administered within the law.