In the first episode of our new Election 2026 series, Litigation and Public Law Partner, Briony Davies, Special Counsel Daniel Fielding and Senior Associate Mark Calderwood, explore New Zealand’s waka jumping legislation and what it means for MPs under the MMP system. They explain how an MP’s seat can be vacated, how the courts have interpreted proportionality, and why legal challenges to party decisions are so difficult to sustain.
[01:40–03:40] Briony introduces the topic of waka jumping and asks Mark to explain what the term means in legal terms. Mark describes waka jumping as the informal label for provisions introduced by the Electoral Integrity Amendment Act 2018, which were designed to preserve public confidence in the electoral system and maintain proportional representation in Parliament under MMP. He explains that New Zealand previously had similar legislation between 2001 and 2005 following significant party defections after the first MMP election, but that no such rules applied between 2005 and 2018. During that gap, MPs were able to leave their parties and remain in Parliament as independents without losing their seats.
[03:40–05:39] The discussion then moves to the mechanics of how an MP’s seat may be vacated under the current legislation. Mark explains that one pathway arises when an MP voluntarily notifies the Speaker that they have resigned from the party for which they were elected, in which case the seat is automatically vacated. He notes that this requirement is applied strictly, as demonstrated by the controversy surrounding Meka Whaitiri’s resignation. Mark then outlines the second pathway, where a party leader may notify the Speaker that an MP’s conduct has distorted or is likely to distort proportionality, provided procedural requirements are met, including notice to the MP, internal party support, and compliance with party rules. He explains that list MPs are replaced by the next person on the party list, while electorate MPs trigger a by‑election, using Jamie Lee Ross departure from the National Party as an illustrative example of how this could have played out.
[05:39–09:19] Attention then shifts to the courts’ interpretation of proportionality, with Briony explaining the significance of the Supreme Court’s decision in Prebble v Huata. She outlines how the case arose from the ACT Party’s attempt to remove Donna Awatere‑Huata from Parliament under the 2001 version of the waka jumping legislation. Briony explains that the Supreme Court held proportionality is distorted simply by an MP continuing to sit in Parliament after ceasing to be a member of the party for which they were elected, regardless of whether the MP left voluntarily or was expelled. She also notes that the Court rejected arguments that voting intentions could cure the distortion, because party membership affects many aspects of parliamentary life, including funding, committee membership, speaking rights, and questions in the House.
[09:19–11:55] Daniel briefly shifts the tone by introducing a pop‑quiz, asking which political party has experienced the most MP defections. The conversation turns to the 1998 split within New Zealand First, during which eight MPs left the party, with five forming Māori Pacific to support the National‑led government. Daniel confirms the answer and notes the irony that New Zealand First itself was founded following Winston Peters’ departure from the National Party.
[11:55–15:48] Briony asks what recourse MPs have when facing expulsion from their parties. Mark explains that decisions made by political parties, particularly where they intersect with statutory powers under the waka jumping legislation, are subject to judicial review. He discusses the High Court’s decision in Tana v Swarbrick, which arose from the Green Party’s investigation into Darlene Tana. Mark explains that the Court found the party had lawfully applied its MP disciplinary process and that Tana had voluntarily resigned her party membership. As a result, the Court declined to grant declarations that the process was unlawful or unfair, clearing the way for the waka jumping provisions to apply. He observes that, despite frequent defections, waka jumping legislation has been successfully used only twice, underscoring the difficulty of resolving political disputes through legal mechanisms.
[16:18–19:47] Briony then asks whether any MPs have successfully challenged their removal. Daniel explains that while no MP has ultimately succeeded in overturning expulsion or removal, Kapa-Kingi has obtained interim relief in her case against Te Pāti Māori. He describes how the High Court reinstated her as a party member on an interim basis, preserving her position as an MP elected for that party pending the substantive judicial review. Daniel notes that the Court identified serious questions regarding alleged procedural unfairness and mistakes of fact, which justified maintaining the status quo until those issues could be fully determined.
[19:47–21:10] The discussion concludes by considering what the Kapa-Kingi case could mean for the upcoming election. Daniel explains that if she ultimately succeeds, her reinstatement would make it difficult for Te Pāti Māori to invoke the waka jumping legislation, although the party could still seek to deselect her as a candidate. If she is unsuccessful, the party could lawfully move to vacate her seat, potentially triggering a by‑election. He notes, however, that timing would be critical, as vacancies arising within six months of a general election may not result in a by‑election if Parliament resolves accordingly under the Electoral Act.
Information in this podcast is correct as at the date of recording, 23 January 2026.
Please contact Briony Davies, Dan Fielding, Mark Calderwood or our Public Law and Litigation team if you need legal advice and guidance on any of the topics discussed in this episode.
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