Former MP Tony Windsor is demanding the High Court find his political nemesis Barnaby Joyce ineligible for office, arguing keeping him in Parliament would amount to a "careless" interpretation of the constitution.
Mr Windsor has joined the case against the Deputy Prime Minister, who is one of seven politicians embroiled in the dual citizenship saga.
Australians with dual citizenship are prevented from being elected to Federal Parliament by section 44 of the constitution.
In August, Mr Joyce revealed he was a New Zealander by descent, because his father was born across the Tasman, and he has since taken steps to renounce his Kiwi status.
Mr Windsor is represented by the former solicitor-general Justin Gleeson, who was involved in a spectacular public brawl with Attorney-General George Brandis last year.
Mr Gleeson and the other members of Mr Windsor's legal team have lodged their submissions in the High Court, slamming arguments by the Attorney-General that Mr Joyce should be allowed to remain in Parliament because he had no way of knowing he was a dual citizen.
They argued ignorance was not a defence, and "acceptance of that argument would reward the careless, and perpetuate the kind of destabilising situations giving rise to the current seven references".
"The diligent prospective candidate, who discovers foreign citizenship by making appropriate inquiries and taking appropriate advice before ticking the [section] 44 box on the nomination form … must take all reasonable steps to divest himself or herself of the status," Mr Windsor's lawyers argued.
"By contrast, the incurious or careless candidate may stand provided the box is ticked and the declaration made without taking appropriate steps.
"The careless candidate is allowed to sit in Parliament."
Mr Windsor retired from Parliament at the 2013 election, and Mr Joyce replaced him as the member for New England.
But after launching fierce criticism of the Deputy Prime Minister, Mr Windsor announced he would contest the seat in 2016.
He was comfortably beaten by the Nationals leader, who now holds the regional New South Wales electorate by more than 8 per cent.