Bye, Bye Barnaby? The Deputy PM Disqualified From Parliament
The High Court has found Deputy Prime Minister Barnaby Joyce to was disqualified from sitting in parliament because of his dual New Zealand citizenship.
He will now have to fight a byelection against Tony Windsor for the seat of New England as early as December 2.
It will be the third federal election in this seat in four years.
The court also found former Greens senators Scott Ludlam and Larissa Waters were not validly elected, along with One Nation's Malcolm Roberts and the National Party's Fiona Nash.
Only Matt Canavan and Nick Xenophon are eligible.
Section 44 of the constitution prevents a subject or citizen of a foreign power from being chosen or sitting as a federal MP.
Since the 2016 election, Mr Turnbull has held onto power with a one-seat majority.
However, it's expected Mr Joyce will hold onto his seat - which has an 8.5
The court found that at the time of his nomination in 2016 Mr Joyce was a New Zealand citizen by descent through his father, James Joyce, who immigrated in 1947.
However, the deputy prime minister only became aware of the possibility he might have NZ citizenship after media inquiries to his office in July.
The NZ high commission informed him that he was an NZ citizen under the law of that country on August 10, and he has since formally renounced the citizenship.
The government argued the phrase "is a subject or a citizen ... of a foreign power" should be seen as only referring to a person who has voluntarily obtained or retained that status.
Mr Windsor, who was a party to the case, argued Mr Joyce knew at the time of nomination his father was born in a country other than Australia, and he ought to have made enquiries and renounced any foreign citizenship held.
Mr Joyce - who spent the day travelling with a media pack across his electorate - was one of seven former and current parliamentarians facing the scrutiny of the High Court, sitting as the Court of Disputed Returns.