Every federal election will spark a "genealogical witch hunt" if the High Court disqualifies Australian-born MPs based on obscure foreign citizenship by descent, lawyers for government senator Matt Canavan say.
On day two of hearings into the "citizenship seven", David Bennett QC argued his client - who stepped aside from cabinet after discovering his Italian dual national status - should be spared the axe.
Mr Bennett said there remains doubt as to whether Senator Canavan even had dual citizenship, with Italian constitutional lawyers still differing over whether a 1983 law change in their country automatically bestowed the status retrospectively on people in his client's situation.
Senator Canavan and his mother Maria were both born in Australia but his maternal grandparents were from Italy. The relevant law change occurred when Senator Canavan was aged just two.
If he does have Italian citizenship, it's because his mother's mother successfully applied for Australian naturalisation after Maria's birth. His grandmother attempted to have Maria naturalised too but the application was rejected on the basis she was "Aust-born".
Mr Bennett argued Senator Canavan's status was so obscured by foreign law and family history it was not reasonable to expect that he would suspect any other citizenship.
"How is Senator a Canavan supposed to work that out? How is anyone supposed to work it out?" he said.
Mr Bennett said disqualifying a natural-born Australian based on a citizenship by descent they did not know about would lead to "genealogical witch hunts every time there is an election."
That would be "totally inappropriate" in a "nation of immigrants" like Australia, he said. The court had to have regard for the "practical consequences" of such a decision.
The court also heard on Wednesday from Brian Walters, lawyers for former Greens senators Scott Ludlam and Larissa Waters - both of whom resigned when they found out about their dual citizenship status. Mr Ludlam was born in New Zealand and Ms Waters in Canada.
"In doing so they complied with their duty to the Parliament and the constitution," Mr Walters told the court.
He believes all five of the others before the court - Senator Canavan, Deputy Prime Minister Barnaby Joyce, deputy Nationals leader Fiona Nash, crossbencher Nick Xenophon, and One Nation's Malcolm Roberts - should all also be shown the door.
All of them, he said, knew they had foreign heritage and should have been more diligent about checking their status, even those born in Australia.
"When they come to the point of nominating for the Senate, and stating on the nomination form that they are not disqualified by section 44 - they have a duty not merely to be honest, but careful," he said.
Section 44 aims to "reinforce confidence" in the Australian Parliament by ensuring it is occupied "by Australians and only by Australians," he said. The section ought not to be given a "tortured" meaning at odds with its literal, textual meaning.
Senator Xenophon's lawyer Andrew Tokley said his client took the necessary steps to renounce both Greek and Cypriot citizenship.
Senator Xenophon has ended up before the court because he was found to have an obscure form of "British overseas" citizenship, because his father was born in Cyprus when it was still a British colony.
"He wasn't aware of facts that would have put a reasonable person on notice that he held British overseas citizenship," Mr Tokley said. "It never even entered his mind that he might be a British overseas citizen."
But Mr Tokley asserts that because this form of citizenship carries with it no right of entry or right of abode - unlike full British citizenship - it should not fall foul section 44.
The hearing continues.
- This story first appeared on The Sydney Morning Herald.