Speaker Trevor Mallard has released two legal opinions on the removal of Martin Matthews as Auditor-General in 2017.

The advice, from Una Jagose, Solicitor-General and Virginia Hardy, Deputy Solicitor-General both say that "a proper basis for removal would be circumstances reasonably (i.e rationally) giving rise to a lack of confidence in the Auditor-General".

"Lack of confidence may relate to concerns about the ability to provide continuing effective leadership of the Audit Office given failings evident in his previous career, or perceptions about such failures, and this factor in turn could encompass issues such as the capacity to maintain or enhance morale within the Office," the letters said.

The advice backs up former Speaker David Carter's decision to ask for Matthews' resignation in 2017. Matthews alleges Carter justified this based on a loss of confidence in him.

Matthews and his lawyer Mary Scholtens said the legislation governing the Auditor-General does not set out a loss of confidence as grounds for dismissal.

READ MORE:

* Ousted Auditor-General Martin Matthews heads back to Parliament

* Judgment is the key issue in the Martin Matthews case

* Speaker Trevor Mallard will receive petition from Martin Matthews

The role is given special legislative protections to safeguard its independence.

A Government isn't allowed to remove an Auditor-General, only Parliament can, and even then only by passing a resolution specifying four strict criteria: disability affecting the performance of duty, bankruptcy, neglect of duty, or misconduct.

Mallard's waiver of legal privilege comes as Matthews' petition to have his case reopened was discussed by the Officers of Parliament Committee.

The Committee appointed Matthews in 2017 before asking for his resignation later that year. It will now consider the process for Matthews' petition.

That could mean hearing from some of the people Matthews has rallied to his defence, among them former Prime Minister Sir Geoffrey Palmer and former Supreme Court judge and International Court of Justice judge Sir Kenneth Keith.

Palmer's submission said "Parliament has done grave damage to a highly qualified officer of state and wrecked his career" and described Matthews' removal as "a constitutional disgrace".

Keith's argued the process followed to remove Matthews breached natural justice" and raised concerns about the protections afforded the Officers of Parliament, which are meant to protect them from political influence.

PHIL JOHNSON/STUFF Former Auditor-General and Ministry of Transport chief executive Martin Matthews.

The Committee will now consider the process for examining the petition. Speaker Trevor Mallard expressed a willingness to hear in person from people who had offered to submit in Matthews' defence.

There was no guarantee these submissions would be heard, although it now appears likely they will be.

Mallard said he did not want to "prejudge the Committee's decision" but given some of the "most eminent jurists in the country" had indicated they wished to submit he would be "reluctant not to pick up their offer to give evidence".

When the Committee next meets, it will decide on the process of how it will go forward.

This could mean it reexamines the case itself, or appoints an independent voice like a retired High Court judge.

At the meeting on Thursday, Matthews submitted evidence in his defence, arguing he was forced to resign.

He submitted alongside Sir Maarten Wevers and former Speaker David Carter. Wevers was the author of a highly critical report into Matthews' appointment as Auditor-General, Carter was Speaker at the time of Matthews' removal.

Carter shocked the room when he said Wevers' report had not been released to the public out of concern for Matthews' mental health.

He said a member of the committee had heard Matthews' mental health was fragile - "the word suicidal was used," he said.

On that basis the committee decided not to table and release the report.

Matthews has until March 11 to respond to that and other submissions.