Matt McKillop
New Zealand First recently announced it would introduce a member’s bill to amend the Legislation Act 2019 by adding definitions of “man” and “woman”. This came shortly after the United Kingdom Supreme Court handed down judgment in For Women Scotland v Scottish Ministers [2025] UKSC 16, a judgment interpreting the Equality Act 2010’s protected characteristic of “sex” to refer exclusively to biological sex.
The judgment was the culmination of efforts from women’s interest groups concerned about circumstances in which transgender women – those whose biological sex does not align with their gender identity – had been apparently required by law to be admitted to services and facilities previously understood to be for biological women only.
The Supreme Court judgment confirms that this apparent understanding was incorrect. The judgment has therefore led to reconsideration of guidance issued under the Equality Act and of the boundaries of sex-based services and practices throughout the United Kingdom.
The concerns motivating these women’s interest groups are diverse, but the most common situations cited in support of their claims include the admission of transgender women to services and facilities where women may face threats of physical or sexual violence or be otherwise vulnerable to predation by men, such as:
- women’s refuges;
- bathrooms and changing rooms;
- prisons; and
- sports involving physical contest.
Similar concerns were raised by New Zealand First in a press release announcing the Bill.
This article does not seek to discuss the extent to which these concerns are actually borne out in substance. It instead addresses whether these worries – which constitute at least part of the apparent motivation for the Legislation (Definitions of Man and Woman) Amendment Bill – require any legislative clarification of statutory sex and gender language in order to be met within New Zealand’s legal framework.
I conclude not. New Zealand law already permits services or facilities for women in most of these circumstances based on biological sex. The Bill would therefore not affect the legal position in those commonly cited circumstances where women might have reasonable concerns about safety and privacy.
What would the Bill do?
The Legislation (Definitions of Man and Woman) Amendment Bill would add ss 13A and 13B to the Legislation Act 2019, which would define sex and gender language used throughout all legislation. The proposed new sections are:
13A Meaning of woman or female
In any legislation, regardless of gender identity–
(a) woman means an adult human biological female; and
(b) in the case of a human being, female means a human biological female.
13B Meaning of man or male
In any legislation, regardless of gender identity–
(a) man means an adult human biological male; and
(b) in the case of a human being, male means a human biological male.
The definitions would apply to every enactment on the books, including every piece of secondary legislation (owing to the expansive definition of “legislation” in s 5(1) of the Legislation Act). There is an immense volume of secondary legislation in New Zealand and it would be therefore a difficult all-of-government task to determine any consequential problems created by the new definitions.
One obvious issue can be identified from the definitions proposed. By defining “woman” as an “adult”, the Bill would exclude non-adults from the abortion services authorised for a pregnant “woman” by the now-reformed Contraception, Sterilisation and Abortion Act. The introduction of the undefined word “adult” ironically introduces a mixed biological and social concept to the proposed definitions of “woman” or “man”. Is a person an “adult” when they reach a certain age, or when they reach a certain stage of biological development?
This interpretive quirk likely only scratches the surface of the problems the Bill would create. But assuming more logical drafting might be adopted by New Zealand First at some point, it is in any event worth examining the motivations behind the Bill to question its necessity in this jurisdiction.
Do the single-sex facility issues being debated in other countries actually arise under New Zealand law? Or is the Bill a solution in search of a problem?
What does New Zealand law already say about single-sex facilities and services?
Human Rights Act 1993
The Human Rights Act 1993 affirms that “sex, which includes pregnancy and childbirth” is a prohibited ground of discrimination. Section 42 requires equal access of all members of the public to places, facilities and vehicles without discrimination. Section 44 prohibits discrimination on the basis of sex in the provision of goods, services or facilities to the public or any section of the public.
Similar protections from sex-based discrimination are contained in the Equality Act 2010. The major issue in For Women Scotland was whether the Equality Act 2010 was referring to biological sex or what the Supreme Court described as “certificated sex”. This refers the sex on government identity documents, which transgender people can seek to change under separate gender recognition legislation.
The same question could be asked of New Zealand’s Human Rights Act. New Zealand also has a legislative process for making changes to “registered sex” under the Births, Deaths, Marriages, and Relationships Registration Act 2021. That Act does not require anyone to treat a birth certificate as definitive proof of someone’s sex or gender but, rather, suggests that a certificate will be a permitted relevant consideration among “any other relevant information” (s 79(2)). A registered sex can include any sex or gender permitted by regulation, which now includes “non-binary” (see Births, Deaths, Marriages, and Relationships Registration (Registering Nominated Sex) Regulations 2023). Registered sex is therefore not bound by a strict binary or biological understanding of sex or gender.
It is clear, though, that the Human Rights Act treats “sex” as a binary and biological concept. The first indication is the definition of “sex” itself, which expressly includes two female biological phenomena (pregnancy and childbirth) as explicit expressions of sex.
The various exceptions to the general duties of access to goods, services and facilities in ss 42 and 44 further illustrate the binary and biological nature of sex in the Human Rights Act. Section 47 creates an exception to s 44 based on different service provision to “men or women”:
47 Exception in relation to skill
Where the nature of a skill varies according to whether it is exercised in relation to men or women, a person does not commit a breach of section 44 by exercising the skill in relation to one sex only, in accordance with that person’s normal practice.
This exception can reflect only a binary (“men or women”) and biological understanding of sex. Medical procedures and physical manipulation techniques might legitimately differ according to sex. But it seems clear that stereotyped social practices amounting to differential treatment would not be exempted by s 47 due to the lack of any technical necessity for differential treatment in the relevant “skill” – for example, a refusal to serve a woman seeking a stereotypically “male” haircut at a barber shop.
Section 49 creates an exception to s 44 in relation to sport, effectively defining the conditions in which single-sex sport is authorised by law. Section 49 provides:
49 Exception in relation to sport
(1) Subject to subsection (2), nothing in section 44 shall prevent the exclusion of persons of one sex from participation in any competitive sporting activity in which the strength, stamina, or physique of competitors is relevant.
(2) Subsection (1) does not apply in relation to the exclusion of persons from participation in–
(a) the coaching of persons engaged in any sporting activity; or
(b) the umpiring or refereeing of any sporting activity; or
(c) the administration of any sporting activity; or
(d) sporting activities by persons who have not attained the age of 12 years.
This exception also reflects a binary and biological understanding of sex. The authority to exclude “persons of one sex” from sport implies there is just one other sex for whom a particular sporting activity is being reserved. The association of “strength, stamina or physique” with sex refers to biologically-grounded differences between men and women. And the carve-out for children under 12 in s 49(2)(d) indicates that pre-pubescent sex segregation in sport is not seen as necessary due to the lack of meaningful biological difference at that age.
Sections 43(1) and 46 each affirm the maintenance or provision of separate facilities or services “for each sex on the ground of public decency or public safety”. While “each” can refer to one member of a group of two or more things, the other exceptions already examined make clear this refers to “each” side of a sex binary.
These exceptions don’t only make clear the binary and biological nature of “sex” in the Human Rights Act. They also show how New Zealand law has long permitted sex-segregated services and facilities in many of the circumstances motivating women’s interest groups in other countries. Single-sex bathroom facilities, sporting teams and services for female victims of sexual offending are all conceivably permitted by the provisions outlined above. Whether or not sex-segregated services are in fact provided in those cases is a matter of practice – not something prevented by law.
Housing transgender prisoners
The final area of frequent concern to women’s interest groups – the arrangements to accommodate transgender prisoners – is not governed by general non-discrimination law, but is instead specifically addressed by a detailed policy contained in both the Corrections Regulations 2005 and the Prison Operations Manual (published on the Corrections website).
A biological sex binary is not rigidly enforced by that process. The regulations’ express contemplation of housing prisoners according to features other than biological sex suggests that the sex definitions inserted by the Bill would have to be ignored for the regulation to be meaningfully operated (since “the context of the legislation requires a different interpretation” – Legislation Act s 9(1)(b)). While this process permits trans women prisoners to be housed in female prisons, it contains some specific exceptions in relation to those who have sexually offended or are accused of doing so.
Even if reform were to be proposed in this area, the existence of specific regulations relating to transgender prisoners and the particular vulnerabilities of transgender prisoners suggests that a general interpretive provision in primary legislation, such as that contained in the proposed Bill, is an inappropriate broad-brush method by which to seek that reform. Transgender prisoners and female prisoners are both vulnerable groups. Anecdotally, trans women and trans men both cannot be housed in men’s prisons without being segregated from other prisoners, for fear of experiencing physical and sexual assault.
Transgender people are protected from discrimination in New Zealand – even though ‘sex’ is biological
While the above analysis suggests sex segregation is permitted by law in certain cases, the biological understanding of “sex” throughout the Human Rights Act does not deprive transgender people of protection from discrimination on the basis of their sex, or any other protected characteristic.
A person who has a different gender identity or physical presentation from their biological sex is protected from differential treatment on the basis of their sex and on the basis that their identity or presentation differs from the expectations of their sex, in the same way that a cisgender person is protected.
This means, for example, that a trans man cannot be discriminated against on the basis on which he presents as trans (that is, that he doesn’t physically or behaviourally conform to the service provider’s expectations of biological women, such as by wearing “male” clothing), in the same way that (to use a hopefully historic example) any woman wearing pants cannot be refused service for her failure to wear a dress.
This isn’t groundbreaking reasoning – even the United States Supreme Court has recently concluded that differential treatment on the basis of sexual orientation or gender identity will necessarily be sex-based treatment (Bostock v Clayton County, Georgia 590 US 644 (2020)). Differential treatment on the basis that the customer or service user is transgender will therefore normally be discriminatory.
So what is the Bill for?
New Zealand law already reflects a biological understanding of sex in most of those areas of greatest concern to women’s interest groups in other countries. The Bill would therefore have no new impact on the regulation of those matters in New Zealand. The remaining area of concern – the accommodation of transgender prisoners – consists of detailed regulations and seeks to address and balance the vulnerabilities of both transgender and female prisoners. The Bill is not a sensible way to address any concerns arising from the secondary legislation and policy governing this issue.
The lack of demonstrated legal need for the Bill, and the many unanticipated issues it would seem to create, suggests secondary motivations to mere protection of women’s interests. The treating of transgender persons and other vulnerable groups as an object of political debate is a concerning trend, which this Bill seems to follow.
Rather than broad-brush reforms that seek to erase transgender persons from legislation, a thoughtful and careful balancing of interests is required.
Matt McKillop is a barrister at Masons Lane Chambers in Wellington, with a practice specialising in public and human rights law
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