Seven federal politicians under a constitutional cloud over their dual citizenships will face a fresh day of questioning when the High Court returns.
The federal government has argued only two parliamentarians - One Nation senator Malcolm Roberts and former Greens senator Scott Ludlum - should be shown the door.
Solicitor-General Stephen Donoghue told the court in Canberra on Monday that those who knew they were foreign citizens, or believed there was a sufficiently high prospect of having foreign ties, ought be disqualified.
Mr Donoghue said both men were born overseas and could not plead ignorance and Senator Roberts did not take all reasonable steps available to renounce his British citizenship.
Meanwhile, the lawyer for Nationals leader Barnaby Joyce and his deputy Fiona Nash argued the pair should not be booted because each tore up their dual citizenships as soon as they were made aware.
Bret Walker SC, representing Mr Joyce and Senator Nash, said neither of them knew until recently they were dual citizens of New Zealand and Britain respectively.
As soon as they found out, they took all reasonable steps required to sever their foreign ties.
Fellow Nationals senator Matt Canavan should also be spared the court's wrath because he was never an Italian citizen to begin with, his lawyer says.
Solicitor-General Stephen Donaghue said Senator Canavan appeared to have acquired Italian citizenship due to a "quirk of history" after an Italian court decided in 1983 that citizenship could be conferred from one's mother.
But David Bennett QC, representing Senator Canavan, said it was in dispute among Italian lawyers that citizenship flowed automatically from the court's decision.
Mr Bennett said "the better view" was that it was a conditional citizenship, which did not apply automatically, and a person would then need to take steps to become an Italian citizen.
Mr Bennett also argued it was irrelevant Senator Canavan's mother registered herself and her children as Italian residents overseas in 2006.
The Commonwealth argues the three Nationals members, along with independent Nick Xenophon and former Greens deputy Larissa Waters, should not be booted because they didn't voluntarily obtain or retain foreign citizenship.
All except Ms Waters were born in Australia and have sworn they had no knowledge the law of another country had made them citizens by descent.