The law in relation to sex and gender is complex involving interaction between the Gender Recognition Act 2004 and the Equality Act 2010.
But the starting point is easy. s.9 of the 2004 Act provides:-
Where a full gender recognition certificate is issued to a person, the person’s gender becomes for all purposes the acquired gender (so that, if the acquired gender is the male gender, the person’s sex becomes that of a man and, if it is the female gender, the person’s sex becomes that of a woman)
Now, note that here it is not someone's "gender" which becomes that of a woman, it is someone's sex. So when the definition of a woman in the 2010 Act at s.212 as "a female of any age" then that definition clearly includes (former) men in possession of a Gender Recognition Certifcate.
Back to the 2010 Act and to its protected characteristics they include at s.7
G Gender reassignment
(1)A person has the protected characteristic of gender reassignment if the person is proposing to undergo, is undergoing or has undergone a process (or part of a process) for the purpose of reassigning the person's sex by changing physiological or other attributes of sex.
(2)A reference to a transsexual person is a reference to a person who has the protected characteristic of gender reassignment.
(3)In relation to the protected characteristic of gender reassignment—
(a)a reference to a person who has a particular protected characteristic is a reference to a transsexual person;
a reference to persons who share a protected characteristic is a reference to transsexual persons.
Now this is to me quite clear. A person with a Gender Recognition Certificate is a woman. So if they seek to access "women only" services and are refused then they are clearly being discriminated against , being possessed of a different protected characteristic. The exemption for "single sex spaces" under s.26 of the 2010 Act is irrelevant to this because these people are, as a matter of law, women.
I have no great desire to enter the toxic debate around The Gender Recognition Act as, as you will see, that is not my purpose here but, for what it is worth, I have no difficulty with any of this. I am in no personal doubt than transsexual people exist and there is no evidence the 2004 Act itself has been abused so that "men" can access women's spaces,
No, my focus is on the law. Not the law relating to transgender rights, the law relating to the devolved competence of the Scottish Parliament.
At present "a woman" is, as a matter, I restate, of law, someone born a woman or someone possessed of a Gender Recognition Certificate under the 2004 Act.
But if the Gender Reform (|Scotland) Bill were to become law, "a woman" would become someone born a woman or someone possessed of a Gender Recognition Certificate under the 2004 Act or (crucially in this context) someone possessed of such a certificate under the putative future Gender Reform (Scotland) Act 2022.
Now on any view, for good or ill, that is a change in law to the definition of "a woman".
This is where I get to the point. Last week there was a decision of the Inner House of the Court of Session in the case of For Women Scotland against The Lord Advocate. It decided that The Gender Representation on Public Boards (Scotland) Act 2018 was beyond the competence of the Scottish Parliament. In passing I'd observe that striking down incompetent Holyrood legislation is by no means the exclusive jurisdiction of the "English" Supreme Court, a point I have made before. The decision had as it's ratio decedendi, a phrase we use daily down Airdrie Sheriff Court,* that in defining a woman as someone who was a woman or lived as a woman, the Scottish Parliament had exceeded its powers, since the definition of a woman was enshrined in the Equality Act and the Equality Act was (by implication) a reserved matter under Schedule 5 of the Scotland Act 1998.
It is a complex and, even for a lawyer, difficult to follow decision but you can cut straight to the chase. The second last paragraph.
" In any event, the definition of woman adopted in the legislation includes those with the protected sex characteristic of women, but only some of those with the protected characteristic of gender reassignment. It qualifies the latter characteristic by protecting only 23 those with that characteristic who are also living as women. The Lord Ordinary stated that the 2018 Act did not redefine “woman” for any other purpose than “to include transgender women as another category” of people who would benefit from the positive measure. Therein lies the rub: “transgender women” is not a category for these purposes; it is not a protected characteristic and for the reasons given, the definition of “woman” adopted in the Act impinges on the nature of protected characteristics which is a reserved matter. Changing the definitions of protected characteristic, even for the purpose of achieving the GRO, is not permitted and in this respect the 2018 Act is outwith legislative competence"
So, if the Gender Recognition Reform (Scotland) Bill seeks to redefine "a woman", as I think it does, then it is beyond the legislative competence of The Scottish Parliament. And since to even introduce it would require the approval of the Law Officers, who must, in terms of paragraph 3(4) of the Ministerial Code sign it off, I suspect we have seen the last of it. If Dorothy Bain thought Lady Dorrian had got For Women Scotland wrong in law she would have been off to the Supreme Court. Noticeably she isn't.
But don't just take my word for that. The Scottish Government is on the record saying the Bill would be introduced before the end of February, Today they are denying having ever said that.
* This is my poor attempt at a joke