The Principles of Legality in Aotearoa New Zealand

Abstract

The principle of legality (POL) may have had a slow start in New Zealand. But a trilogy of Supreme Court decisions in 2021 – D v Police, Fitzgerald v R and Trans-Tasman Resources v Taranaki-Whanganui Conservation Board – as well as a significant case law generated by the Covid-19 pandemic, have ensured the principle’s meteoric rise. Interpretive presumptions protective of basic norms are emerging as a central and perhaps defining feature of contemporary public law in Aotearoa, and are destined to be at the heart of future legal development.

It follows that the POL should be a key focus for all public lawyers. The principle is typically taken to mean that if Parliament wishes to infringe basic legal norms it must do so through express statutory language or by necessary implication.

This article unpacks the legality jurisprudence. First, it analyses the ‘triggers’ for the POL. That is, the norms which enliven the interpretive principle. While the POL is traditionally associated with protection of common law rights, the triggers have expanded significantly over time. The article examines four types of trigger: common law rights; principles of the Treaty of Waitangi (and tikanga/Māori customary law); international law; and statutory norms, specifically rights under the New Zealand Bill of Rights Act 1990.

The article next examines the legality principle itself. While legal actors often refer to the POL as if it were a monolithic principle, this article demonstrates that there are multiple variants of the principle which are meaningfully different. As such unqualified references to the ‘principle of legality’ are liable to mislead.

It is typical for particular areas of law, such as human rights, private law, international law or the Treaty of Waitangi, to be analysed in isolation. But as this article demonstrates, there is significant insight to be gained by setting these different norms, and associated interpretive principles, side-by-side. Doing so causes us to reflect upon variations between these areas, both in relation to selection of trigger norms and the strength of interpretive presumptions, and whether variations are capable of rationalisation.

Key recent cases considered include:
Ellis v R [2022] NZSC 114
Trans-Tasman Resources Ltd v Taranaki-Whanganui Conservation Board [2021] NZSC 127
D v Police [2021] NZSC 2
Fitzgerald v R [2021] NZSC 131
Borrowdale v Director-General of Health [2021] NZCA 520
Four Midwives v Minister for Covid-19 Response [2021] NZHC 3064
Four Aviation Security Service Employees v Minister for Covid-19 Response [2021] NZHC 3012

Keywords: principle of legality, statutory interpretation, rights, private law, human rights, New Zealand Bill of Rights Act 1990, Treaty of Waitangi, international law, tikanga, customary law, covid, judicial review, administrative law, constitutional law

JEL Classification: K23, K33, K40