Election 2026 | Jumping Ship: Waka-jumping, parliamentary proportionality and the courts

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 aros

For show notes and additional resources visit minterellison.co.nz/podcasts