The dual citizenship debacle that has engulfed Australian politics will be back before the High Court in Canberra for a hearing in October.
Four senators and deputy prime minister Barnaby Joyce were referred to the court earlier this month after it was revealed they did not meet the sole citizenship requirement of section 44 of the constitution.
South Australian Senator Nick Xenophon and NSW Senator Fiona Nash will also be referred to the court over their British citizenship by descent when federal parliament next sits in September.
At a directions hearing held in Brisbane on Thursday, Chief Justice Susan Kiefel set the matter down for a three-day hearing in Canberra from October 10.
One Nation Senator Malcolm Roberts remains the most at risk of being disqualified from parliament as he may have officially renounced his British citizenship after his nomination, the court heard.
Solicitor-General Stephen Donaghue QC said there was a "clear demarcation line" between the politicians - those who had known they were a citizen of a foreign power and those who did not.
Under section 44 of the constitution a person is incapable of being elected to the parliament if they are a "citizen or entitled to the rights or privileges of a subject or a citizen of a foreign power".
Mr Joyce has been found to have been a New Zealand citizen by descent but the government has advice this isn't enough to unseat him.
If the court finds him to be ineligible, it will trigger a by-election in his NSW seat of New England, and potentially put at risk the government's one-seat majority in the lower house.
The court will also examine stood-aside cabinet minister Matt Canavan, who has Italian heritage on his mother's side.
Like Senator Roberts, former Greens senators Larissa Waters and Scott Ludlam were also born overseas.
