Following the Supreme Court’s decision in For Women Scotland Ltd v The Scottish Ministers [2025] UKSC 16 (“FWS”), there has been much public debate about the lawfulness of policies adopted by employers and service providers that permit trans people to access toilets and changing room facilities in their acquired sex. To date, the issue of the lawfulness of such “trans-inclusive” provision has been addressed in several first-instance court and tribunal decisions. It has been argued in these cases that it is unlawful for service providers and employers to permit trans people to access toilets and changing room facilities in their acquired sex, and that service providers and employers opting for such “trans-inclusive” provision are either harassing or directly or indirectly discriminating against the non-trans men and women who share those facilities with them. Thus far, these actions have only succeeded against employers, rather than service providers or trans people themselves. (See the employment tribunal decisions in B Hutchinson v County Durham and Darlington NHS Foundation Trust [2026] and Sandie Peggie v Fife Health Board and another [2025]; and compare BM Kelly v Leonardo UK Ltd [2025]). The lawfulness of trans-inclusive provision in services and employment was also considered in Swift J’s judgment in the recent judicial review in Good Law Project v The Commission for Equality and Human Rights [2026] EWHC 279 (“GLP v EHRC”), which held that the Equality and Human Rights Commission’s (now withdrawn) “interim update” had been lawful. Most of these decisions are now subject to appeal. 

I will argue in this post that, notwithstanding the Supreme Court’s finding in FWS that sex means “biological sex” for the purposes of the EA 2010, there is a strong basis in law for rejecting arguments to the effect that trans-inclusive provision is unlawful. I will make three claims in support of an argument that trans-inclusive provision should be regarded as lawful: 

1. That the jurisprudence of the European Court of Human Rights (ECtHR) on the Article 8 rights of trans people extends beyond the need for formal gender recognition (or “civil status”). Legal gender recognition must, in addition, address the need to avoid unnecessary discordance between an individual’s social reality and their legal status. The ECtHR’s jurisprudence has also cast significant doubt on the underlying coherence of “biological sex” as a basis for permanent social segregation.
2. That notwithstanding the Supreme Court’s finding in FWS that trans people do not change their “biological sex” for the purposes of the EA 2010, the process of “gender reassignment” contemplated by section 7 protects the freedom of trans people to reassign their sex for the purposes of accessing segregated services and facilities. A rule or policy that requires the permanent exclusion of trans people in their acquired sex will directly discriminate against them. 
3. Relatedly, that it is open to courts in the UK to interpret domestic legislation in a manner that accommodates the lawfulness of trans inclusion. There is a strong basis in law for them to do so.  

Following FWS, there has been an understandable tendency, both in public debate and in courtrooms, to overstate the broader significance of the meaning of terms like “man” and “woman” in law. But within ECtHR as well as British and European courts, the case law that led to the recognition of the rights of trans people in UK law was never focused on this narrow semantic question.  Instead, the relevant law was (and remains) focussed on the autonomy and self-development of trans people—their freedom to reassign all of the attributes of their sex that they may possibly reassign, and their right to live under a legal regime that does not create discordance between the social reality they have created and their legal status. 

1. Social Segregation and Gender Recognition in the ECtHR

No one disputes that under Article 8 member states have an obligation towards trans people “to provide quick, transparent and accessible procedures for changing the registered sex marker of transgender people” (see A.D. and Others v Georgia, Case Nos. 57864/17, 79087/17 and 55353/19)); X v The Former Yugoslav Republic of Macedonia Case No. 29683/16). However, a consensus has emerged among those who argue for the permanent and complete exclusion of trans people from all services designated for their acquired sex that conforming with this obligation will be sufficient. Supposedly, so long as a process is available for changing these markers for the purpose of civil recognition (on birth and marriage certificates, for example) there will be no infringement of rights, even if widespread derogations are made elsewhere. In Swift J’s recent judgment in GLP v EHRC, he refers to the ECtHR’s judgments as relating narrowly to matters of “civil status” (at [97]-[98]).  A similar argument was recently offered on this blog by Michael Foran. 

I think these arguments have become implausibly detached from the legal and factual context in which I v the United Kingdom (no. 25680/94) and Goodwin v the United Kingdom (no. 28957/95), were decided. They fail to take seriously the increasingly serious incursions on the privacy rights of trans people that are likely to occur if the trans-exclusionary interpretation of domestic law prevails. In its decision in Goodwin, in fact, the ECtHR stressed the need to avoid any unnecessary discordance between an individual’s social reality and their legal status ([77]). Christine Goodwin’s original complaints included that she was “considered in law to be a man” for the purposes of discrimination law, and she raised concerns that her employer had disclosed her identity to her colleagues (who she feared had begun gossiping about her) ([15]).

The ECtHR has also repeatedly stressed that because “the right to gender identity and personal development is a fundamental aspect of the right to respect for private life, the States have only a narrow margin of appreciation in that area” (TH v Czech Republic, Case No. 33037/22). Furthermore, it has affirmed that it is “of crucial importance that the Convention is interpreted and applied in a manner which renders its rights practical and effective, not theoretical and illusory” (YY v Turkey, Case No. 14793/08). A regime in which trans-inclusive provision was treated as unlawful would have the effect of undercutting legal gender recognition across broad swathes of public life. It would license a situation in which service providers and employers could routinely subject trans people to intrusive confrontation and inquiry. It would frequently require trans people to disclose their birth sex in the course of employment or when accessing sex-segregated services. There is, in this regard, a considerable line of authority on gender reassignment in the ECtHR that relates to legal arrangements that compel trans people to disclose their birth sex when they provide identification (beginning perhaps with B v France, Case No. 13343/87). Any difference between requiring trans people to present proof of identity that will disclose their birth sex and requiring employers and service providers to question whether the documents that would ordinarily prove identity verify their “true sex” is a difference in form rather than substance.

In both I and Goodwin, moreover, the ECtHR expressed profound doubts about “biological sex” as principled basis for the differential treatment of trans people. The relevant passage from Goodwin merits being quoted in full: 

While it also remains the case that a transsexual cannot acquire all the biological characteristics of the assigned sex… the Court notes that with increasingly sophisticated surgery and types of hormonal treatments, the principal unchanging biological aspect of gender identity is the chromosomal element. It is known however that chromosomal anomalies may arise naturally (for example, in cases of intersex conditions where the biological criteria at birth are not congruent) and in those cases, some persons have to be assigned to one sex or the other as seems most appropriate in the circumstances of the individual case. It is not apparent to the Court that the chromosomal element, amongst all the others, must inevitably take on decisive significance for the purposes of legal attribution of gender identity for transsexuals (see the dissenting opinion of Thorpe LJ in Bellinger v. Bellinger cited in paragraph 52 above; and the judgment of Chisholm J in the Australian case, Re Kevin, cited in paragraph 55 above.)

The approving references to Thorpe LJ’s dissenting opinion in Bellinger and Chisholm J’s magisterial and forensic dissection of the traditional legal approach to determining “biological sex” are instructive. (Chisholm J’s judgment bears rereading.) To the extent that trans people are unable to change biological attributes of their sex, the ECtHR has recognised that it would be irrational or unreasonable to make these immutable sex characteristics a basis for preventing broader reassignment. 

None of this reasoning definitively precludes the success of a novel argument to the effect that it is “necessary in a democratic society” in order to address some “pressing social need” to place limitations on gender recognition in some area of law (cf. YY v Turkey, [100]). But it does suggest that any legal framework to this effect will need to be formulated precisely and carefully, and that the “utmost care and precision is required” when recognition is denied on “biological” grounds (cf. A.D. and Others v Georgia, [75]).

2. The Protected Characteristic of Gender Reassignment 

Section 7 of the EA 2010, which recognises the protected characteristic of “gender reassignment”, is one of the core legislative provisions protecting the rights of trans people in the UK. The core observation to be made in interpreting s. 7 is that it directly contemplates that individuals will undertake a process “to reassign their sex by changing physiological or other attributes of sex”. As I have noted previously, on its plain and ordinary meaning this provision is best interpreted as contemplating the reassignment of legal sex. In its very short discussion of the provision in FWS, however, the Supreme Court rejected this analysis (at [200]). Nonetheless, a finding that there are aspects of a person’s sex that resist reassignment should not license the more dramatic conclusion that s. 7 no longer protects a person’s freedom to reassign all those aspects of their sex that they are able to reassign. 

For our purposes it is useful to note, first, that the provision contemplates the possibility that a person might reassign all of the physiological attributes of their sex that it is possible to reassign. Second, and more crucially, as the legislation also acknowledges, this reassignment will include other attributes of sex, including its psychological and social attributes. A person may well change the pronouns they use to describe themselves, their dress and external appearance, and the sex with which they are identified by others for the purpose of conforming with various social and legal norms. It was acknowledged in the European Court of Justice decision that eventually led to the recognition of gender reassignment as a protected characteristic that to treat a person unfavourably on the basis of their reassignment would amount to “a failure to respect the dignity and freedom to which he or she is entitled” (Case C-13/94 P v S and Cornwall County [1996] E.C.R. I-2143, [22]). This provision protects a person’s liberty to reassign all of the attributes of sex that they are capable of reassignment.

Proponents of trans-exclusion often argue that a trans person who is excluded from sex-segregated services or facilities has not been treated less favourably than anyone else of the same “biological sex”. It is true that UK courts have held that the legal sex of the comparator in a claim for direct gender reassignment discrimination will usually be the sex of the individual before they began reassignment (see e.g. FWS, [134],  A v Chief Constable of West Yorkshire Police [2004] UKHL 21, [56] per Lady Hale; R (on the application of Green) v Secretary of State for Justice [2013] EWHC 3491). But these cases should not be read as requiring a narrow focus on the sex of the comparator to become a means for frustrating the very possibility of reassignment. The emphasis on the previous sex of the comparator in these cases reflected the idea that although gender reassignment discrimination is a form of sex discrimination, “there is no requirement for a male/female comparison to be made” in these cases (Chessington World of Adventures Ltd v Reed [1998] ICR 97, p. 104).  For instance, the comparator cannot be selected in a way that allows someone to avoid liability for gender reassignment discrimination against a trans woman by arguing that they would have treated any other woman equally unfavourably. Very often, the appropriate comparator will therefore be a person in the position of the claimant before they began the process of reassignment, and thus a person who is of the sex to which the claimant used to belong (P v S, [21]). In this respect, to treat a claimant unfavourably because they have reassigned the social characteristics of their sex is to treat them less favourably than they would have been treated if they had not undergone the relevant process of reassignment. 

Suppose that an employer adopts a rule that employees may not adopt pronouns associated with the opposing ‘biological sex’. It may be argued that such a policy is neither direct sex discrimination nor direct gender reassignment discrimination. People of both sexes are treated equally by the policy, and a trans woman prevented from reassigning her pronouns to ‘she’ and ‘her’ has not been treated less favourably than any other ‘biological male’. But this argument misuses the sex of the comparator. If a trans woman’s employment is terminated for violating the pronoun policy, her unfavourable treatment results from undertaking the very process of reassignment contemplated by s. 7. No other employee has received this treatment. Her reassignment of her pronouns is the only reason for her unfavourable treatment. Crucially, however, a trans man who had changed his pronouns to ‘he’ and ‘him’ would receive the same unfavourable treatment under the policy. When a policy is designed to prevent people of either sex from reassignment, the sex of the comparator is immaterial — a comparator of either sex would not have received the unfavourable treatment for this reason.

This analysis extends straightforwardly to policies that treat a person unfavourably because they seek to reassign the sex of the lavatories or changing rooms that they use. This has always formed part of the ordinary process of reassignment of the non-physiological attributes of sex. When applied to them, a rule or policy that purports to prevent an individual from undertaking such reassignment will result in treatment that is less favourable to them. There is an “exact correspondence” between the protected characteristic and the unfavourable treatment (Bull (And Another) v Hall (And Another) [2013] UKSC 73, [18]-[32] per Lady Hale). In this respect, when a rule or policy segregates on the basis of sex, the sex of the comparator is therefore immaterial to the question of whether someone with the protected characteristic of gender reassignment has been treated unfavourably. A trans person of either birth sex would receive the less favourable treatment; a non-trans person of either birth sex would not. 

A version of this argument was presented forcefully by Dinah Rose KC before the Court of Appeal in Croft v Royal Mail [2003] EWCA Civ 1045. The Court of Appeal accepted it in a qualified form, acknowledging that a permanent exclusion of the appellant Sarah Croft from the facilities intended for her acquired sex would have been direct discrimination against her. In this respect, the sex of Croft’s hypothetical comparator was immaterial to the analysis ([74], per Parker LJ). Whether the comparator is male or female, they would not have been treated unfavourably in the same manner, since they would not have been denied a choice that is valued by them (cf. R v Birmingham City Council ex parte Equal Opportunities Commission [1989] AC 1155, p. 1193 per Lord Goff). In FWS, the Supreme Court referred to Croft with apparent approval, noting that the sex of the comparator in a claim for direct gender reassignment discrimination may be immaterial to the analysis (FWS, [134]). 

3. Permitting or Requiring Exclusion? 

Given that the Court in FWS confirmed that, for the purposes of the EA 2010, “sex” means “biological sex”, it might be thought that the UK’s domestic law clearly prohibits trans people from accessing services in their acquired sex. Much public debate in the UK following FWS has proceeded on this assumption. I do not think it was warranted, and I do not think that the Court’s reasoning in FWS precludes the lawful provision of trans-inclusive services and facilities. In FWS, in fact, the Court noted the absurdity of an interpretation that would require service providers to ignore material circumstances of a trans person’s appearance in providing sex-segregated services (see [213]-[218]). This absurdity would be mirrored by a finding that required service providers and employers to ignore similar circumstances that would make it irrational or unreasonable for others to object to a trans or intersex person’s presence in these facilities.

There are two pieces of legislation that are said to compel a finding that trans inclusive provision in services and employment is unlawful. The first are the provisions of Schedule 3 of the Equality Act 2010, which permit the provision of sex-segregated services and facilities. The second is the Workplace (Health, Safety and Welfare) Regulations 1992 (“the 1992 Regulations”), which require employers to offer separate sex sanitary conveniences and facilities for washing themselves and changing clothing. Both sets of provisions were addressed in Swift J’s judgment in GLP v EHRC. 

In the case of Schedule 3 of the EA 2010, its terms are permissive, rather than mandatory. As Swift J suggests in his dicta in (at [57]-[62], [99]), trans-inclusive provision of services and facilities will often be lawful. Where it is lawful, it will need to be considered as a reasonable alternative to completely sex-segregated provision. 

In GLP v EHRC, Swift J held that the 1992 Regulations required a “biological sex” interpretation. An employer who in “good faith adopted and applied a policy that the female lavatories were available only to biological women and the male ones only available to biological men” would “do what is required” by the 1992 Regulations ([40]). The trans and intersex claimants have applied for permission to appeal on this point. Even supposing that Swift J’s judgment is correct in this regard, however, it should be noted that he regarded the regulations as setting a floor, rather than a ceiling, for provision in an employment setting ([27]). To the extent that the regulations require “sufficient” provision that is strictly segregated on the basis of “biological sex”, they also permit employers to make other provision. Employers must also ensure that the provision they make is not “discriminatory on the ground of gender reassignment” ([42]).  This suggests that provision of trans-inclusive services for women and men that goes beyond what is sufficient for the purposes of the 1992 regulations will be lawful. An employer can comply with the 1992 Regulations and provide trans-inclusive facilities—the two possibilities are not inconsistent.

I am, for my own part, not convinced that on a careful reading the meaning of the terms of “men” and women” has much of an effect on the operation of the 1992 Regulations. For instance, on any interpretation the requirement in regulation 25 that “suitable facilities shall be provided for any person at work who is a pregnant woman or nursing mother to rest” does not give rise to any difficulties for trans-inclusive provision. The only requirement is to provide these facilities as part of the physical estate. These facilities might then be used by a person of either sex (such as a pregnant trans man or a breastfeeding trans woman).   Even on a “biological sex” interpretation, moreover, it would be difficult to argue that (for example) the decision to accommodate an individual trans person in their acquired sex would amount to a failure to provide “separate rooms containing conveniences for men and women” contrary to the proper purpose of regulation 20. It is particularly implausible to interpret these provisions as requiring employers to adopt rules or policies that would harass or discriminate against intersex and trans employees—some of whom have been accessing facilities at work in their acquired sex for decades—by now excluding them and outing them to their colleagues in the process. I think it would be absurd to conclude, more than 30 years after their enactment, that the 1992 Regulations had the effect of criminally prohibiting policies that would allow trans people to eventually use toilets in their acquired sex. 

4. Conclusion: Liberalism and Common Sense

In the United States, The State of Kansas has recently passed SB 244—the so-called “bathroom bounty” bill. The bill allows anyone who is “aggrieved” because a trans person has used a multiple-occupancy bathroom or changing room in their acquired sex to bring a cause of action against that person, and to recover either “actual damages or liquidated damages in the amount of $1000”.  It is hard to find any consensus in this area, but I hope that many British readers will agree with me that laws of the sort are dangerously intrusive and illiberal. They prohibit, categorically, the accommodation of trans people in the sex in which they live. They treat their presence in these services as an intrinsic wrong—as a mark of deception and delusion. If British law were interpreted as requiring a similar approach, it would involve several serious mistakes of law and principle. 

Writing extra-judicially at the beginning of the 21^st century, Lord Reed celebrated the “libertarian, or at least laissez faire” approach taken to sex and gender in the UK. Lord Reed noted that:

“[T]he relatively informal nature of administrative arrangements in the United Kingdom enables many other potential problems to be avoided through the application of common sense: for example, whether a trans-sexual sentenced to a term of imprisonment should be held with men or with women; or whether she should be treated in hospital in a male or female ward. Issues of this kind are not dependent on legal status, but are resolved on the basis of individual circumstances.” 

Employers and service providers who have accommodated trans-people in their acquired sex have done no more than adopt the liberal, common-sense attitude that Lord Reed once celebrated. If the proposal to treat trans-inclusive services as unlawful and intrinsically wrongful is followed, it would represent a radical departure from the laissez-faire approach that has prevailed in the United Kingdom for several decades. It would be an unprecedented regression for the UK, which would infringe the Article 8 rights of trans people. Fortunately, even following FWS, there is nothing in the UK’s domestic legal arrangements that should require such a regression. 

Robert Mullins is an Associate Professor of the TC Beirne School of Law at The University of Queensland. The author would like to thank Paul F. Scott and Leah Trueblood for their insightful comments on earlier drafts of this post. 

(Suggested citation: R. Mullins, ‘“Biological Sex”, Social Segregation, and the Freedom to Reassign Sex’, U.K. Const. L. Blog (9th March 2026) (available at https://ukconstitutionallaw.org/))