On Friday Mallard answered a written question from the National Party about the defamation suit - the plaintiff received a lump sum payment of $158,000 and $175,641 was spent on legal fees.
National's Shadow Leader of the House Chris Bishop said taxpayers deserved some answers as to why they were footing the bill for his "reckless comments" and why he would not stand down as Speaker.
Bishop is not on that committee but will sub in for Nicola Grigg. Labour has the majority in the committee.
"So far there has been no apology to Parliament, no statement, and no accountability. This is not good enough," said Bishop.
After Mallard released details of the court costs, National and Act said they'd lost confidence in the Speaker and called for him to resign. Both parties voted for Mallard before details of the case were released.
With Labour's outright majority in the House a motion of no confidence would only pass if Mallard lost the confidence of his own party.
But Prime Minister Jacinda Ardern continued to back Mallard despite his "mistake".
"My view is obviously, and he agrees, he made a mistake. No one is debating that. But does that change my view that he is the right person for the job? No it doesn't.
"We have to acknowledge as well that the Speaker role, despite being independent of the Government, is a politicised position. There'll be very few Speakers at some point that hasn't had an Opposition party call a confidence vote."
Ardern said she'd spoken to Mallard about ensuring he remained answerable to Parliament and it was the decision to appear before the Select Committee on Wednesday.
Mallard is a Labour MP but the Speaker is an independent position which sits outside Government.
Mallard's case was handled by Deputy Speaker Anne Tolley, then a National MP, and it was considered that because the Speaker is the Minister responsible for Parliamentary Services, the same rules should apply as for ministers.
The process for Mallard's legal costs was signed off by Tolley rather than Cabinet.
The Parliamentary Service Commission - a cross-party group of MPs - expanded the rules for which legal costs can be covered to include advice, representation and damages or settlements.
It's understood the change was made because to align the policy for members' legal costs with the costs that Ministers can be indemnified for and settlement costs were added as they would be more cost effective in many cases than going through lengthy court litigation.
Those applications have to be signed off by the party leader, the Speaker and chief executive of Parliamentary Service.
This is a separate process than the one which the Speaker followed as legal advice from Crown Law stated his stature was aligned with a Cabinet minister which have always been able to have settlements covered by taxpayers.