Organisers of the 'Defy Definition' protests estimated more than 10,000 people marched across five New Zealand cities on 14 June 2026, opposing NZ First's member's bill to write biological definitions of 'woman' and 'man' into law.

The Legislation (Definitions of Woman and Man) Amendment Bill, introduced by NZ First, would define 'woman' as 'an adult human biological female' and 'man' as 'an adult human biological male' across New Zealand legislation. The bill is before a select committee and open to public submissions. Thousands marched through downtown Auckland as the largest single-city contingent, according to NZ Herald reporting from 12 June.

Protest organisers framed the bill as erasing transgender people from legal recognition and said they would not stop campaigning until it was defeated, according to RNZ. That framing goes to the core of the legislative dispute: whether a statutory definition anchored in biological sex removes meaningful legal standing for people whose gender identity differs from their sex at birth.

The bill's supporters in NZ First argue the opposite — that clarity in statute is necessary because the existing body of New Zealand law uses 'woman' and 'man' inconsistently and without biological grounding, creating uncertainty in areas from single-sex service provision to sports eligibility. Critics, including those who turned out on Saturday, contend that embedding biological sex as the sole legislative referent will flow through to rights and protections that transgender New Zealanders currently rely on.

Member's bills of this kind move slowly. The bill will complete its select committee process — including the public submission round now under way — before any second reading, and the parliamentary arithmetic in the current House means its fate is not predetermined. NZ First holds the bill but needs coalition partners to carry it into law; National and ACT have not publicly committed to supporting it in its current form.

The scale of street opposition is notable by recent New Zealand standards, though organiser estimates and actual crowd counts frequently diverge, and no independent tally has been published. What is clear is that the bill has activated sustained, organised opposition well before it reaches a vote — a dynamic that will shape how coalition parties calculate the political cost of their positions as the select committee process continues.

Public submissions on the bill remain open, giving opponents and supporters alike a formal channel to Parliament alongside the street pressure.