The attorney general, George Brandis, has attempted to save the political careers of three government MPs by claiming they should not be punished for not knowing they held dual citizenship.

In his submissions to the high court, Brandis argues that the section 44 phrase “is a subject of a citizen … of a foreign power” should only be applied to someone who has “voluntarily obtained or retained” that citizenship.

Anyone else, which the government has so far argued includes the case of deputy prime minister, Barnaby Joyce, and senators Fiona Nash, Matt Canavan and Nick Xenophon – who all found themselves in front of the high court after discovering they were citizens of another country by descent – should not be considered to have breached the constitution.

“A person who does not know that they are, or ever were, a foreign citizen has not voluntarily obtained that status,” Brandis submitted to the court on Tuesday.

“A person who becomes aware that he or she is a foreign citizen, or who becomes aware [ie subjectively appreciates] that there is a considerable, serious or sizeable prospect that he or she has that status, voluntarily retains that status unless he or she takes all reasonable steps to renounce it within a reasonable time of becoming so aware.

“Alternatively, where a person has no knowledge that they are, or ever were, a foreign citizen, the requirement to take ‘all reasonable steps’ to renounce that foreign citizenship does not require the person to take any steps. Taking no steps is reasonable in these circumstances,” Brandis said.

Brandis argued that the varieties of international law had impacted some people’s attempts to clarify their position.



“For example, Senator Canavan’s case requires an understanding of the retrospective effect of rulings of the Italian constitutional court on longstanding statutes. Senator Xenophon’s case illustrates that even when inquiries are made, directed to renouncing foreign citizenship, it is possible in good faith to fail to recognise the possibility that a person is the ‘beneficiary’ of foreign citizenship by reason of the operation of long-repealed foreign laws on facts that occurred decades ago.

“Mr Joyce’s case likewise illustrates the potential for reasonable inquiries to generate incorrect information, for his affidavit discloses that, when he first made inquiries as to whether he was a citizen of New Zealand, his staff were advised by the New Zealand high commission and the New Zealand Department of Internal Affairs that it was necessary to apply in order to become a New Zealand citizen.”

Greens senator Larissa Waters, who resigned in July after discovering she still held Canadian citizenship, a fact she was criticised for by members of the government, is another example being held up under the Brandis defence.



But One Nation senator Malcolm Roberts, found by the high court last week to have held dual citizenship when he nominated, and Greens senator Scott Ludlam, who started the section 44 concerns after discovering he still held New Zealand citizenship, were different, Brandis argued.

“Applying either approach, Mr Ludlam and Senator Roberts were incapable of being chosen as senators,” Brandis claimed. “The resultant vacancies should be filled by a special count. The other referred persons are not disqualified.”

Before the court case, Canavan had said publicly that his mother had signed him up for Italian citizenship, without his knowledge, when he was 25.

But his lawyers argued before the high court that further investigations had revealed he had become a citizen by descent when he was two.

Roberts originally claimed he was never a citizen of any nation other than Australia.

He then submitted to the court he had taken steps to renounce his British citizenship, which he came by from his Welsh-born father, before he nominated to the Senate.

Last week, following a cross examination, the court ruled that Roberts was a dual citizen at the time of his nomination.

His legal defence will now centre on whether sending emails to an invalid address constitutes “reasonable steps” to renounce that citizenship.

Ludlam is not challenging his case.

Joyce was discovered to have held New Zealand citizenship through his father, while Nash undertook her own investigations and discovered she held dual-citizenship through her Scottish-born father.

The court’s decision will be seen as helping to lay out the framework as to what is considered a dual citizen under the constitution, which was written decades before Australian citizenship existed.

It is scheduled to hear the cases of those MPs involved between 10 and 12 October.