Amid the 2017–18 Australian parliamentary eligibility crisis, the trigger for the by-election was the judgment of the High Court of Australia sitting as the Court of Disputed Returns on 27 October 2017, which found that the sitting member, Deputy Prime Minister and Nationals leader Barnaby Joyce, was ineligible under Section 44 of the Constitution to sit in the Parliament of Australia, by virtue of holding New Zealand citizenship at the time of his nomination and election. The seat was declared vacant by the High Court on the same day. Joyce had renounced his dual citizenship effective from August in order to become a sole citizen of Australia, and was thus eligible to run for the by-election.