"The comparator in a discrimination claim for a male with GRC would be a woman, not a man. You would have to therefore have a strong basis for demonstrating a proportionate means (exclusion of legally female male person) of achieving a legitimate aim (single sex space where particularly needed)"
I honestly don't think it makes a difference.
Some scenarios:
a transman with a GRC is rejected for employment in a nursery on the grounds of 'we don't employ men' - the transman would have a claim for sex discrimation, because their sex is 'male' and the other staff are 'female'
a transman without a GRC is rejected similarly - no case of sex discrimination, because their sex is legally female, however you could claim for 'gender reassignment' discrimination on the basis that a person of the female sex who did not identify as transgender would not have this issue
a transwoman with a GRC is rejected to work with female rape victims - no case for sex discrimination because TW w/GRC's sex is female, but has case for gender reassignment discrimination, which could likely be defended against
a transwoman without a GRC is rejected similarly - could claim for both sex discrimination as (male) AND gender reassignment discrimination, both claims could be defended against.
Note that there is no longer a Sex Discrimination Act, it's under the same Equality Act 2010
In terms of the differences between sex discrimination and gender reassignment discrimination:
- you can provide single sex services IF
(a) only persons of that sex have need of the service.
(b) you also provide mixed sex services, but offering single sex services as well is 'more effective'
(c) a joint service would be 'less effective', and your service is disproportionately required by one sex
(d) at hospital/care facility/similar
(e) you provide services to two or more people at once, and one of those people might 'reasonably object' to a person of the opposite sex
(f) the service involves physical contact, and the service provider might 'reasonably object' to providing it to a member of the opposite sex
AND this is a 'proportionate means of achieving a legitimate aim'
Whereas gender reassignment discrimination is allowed in:
(a) providing separate sex services
(b)providing different services to each sex
(c)providing single-sex services
where this is a 'proportionate means of achieving a legitimate aim.'
It would seem that given that you must show that a single/separate sex service is of itself 'more effective', as in a hospital ward, then there isn't really an obvious difference between a 'man' and a 'transwoman' given that the 'transwoman' may appear to other service users to be a 'man', although perhaps this varies from case to case.
Otherwise in terms of the hypothetical TW with GRC, if they are excluded from a female service, that exclusion would therefore be on the grounds of 'gender reassignment', which does not reference a GRC, or the person's sex - it purely stands on the fact that the person is transgender.
I think there is considerable confusion, because the original transgender discrimination legislation was the Sex Discrimination Gender Reassignment Regulations 1999, which modified the Sex Discrimination Act of 1975 to apply to employment
www.legislation.gov.uk/uksi/1999/1102/regulation/2/made
however it specifically did NOT cover Part III of the SDA, which covers services.
So 1999 introduced SDA 1975 2A 'Discrimination on the grounds of gender reassignment' but created exceptions on the basis of 'genuine occupational requirement'
However the GRA 2004 said, at schedule 6, www.legislation.gov.uk/ukpga/2004/7/pdfs/ukpga_20040007_en.pdf (substituting into the SDA 1975) that you could NOT discriminate against people, even with a genuine occupational requirement, IF they had a GRC.
The Equality Act repealed the SDA 1975 (which, as modified by the GRA, did reference GRCs), and there is not one mention of the GRC in the Equality Act.
Clearly if I refuse service to a person who is legally female, on the grounds that they are not biologically female and I want to provide services to only females, then I am discriminating on the grounds of 'gender reassignment', so the GRC doesn't come into it except to preclude them from claiming 'sex discrimination'
The only place I can see a GRC making a legal difference (accepting, of course, that a public body might choose to recognise a GRC without being required to) is that there are MANY different types of discrimination, and there is NOT a generalised exception in each case.
For example, we can refuse to offer a service to a transgender person, GRC, or not, if we satisfy the exceptions discussed above.
However, the Equality Act of instance covers Higher Education admissions. This covers all types of discrimination except marriage and civil partnership. Hence discrimination in admissions on the grounds of sex or gender assignment (inter alia) are unlawful, but there is an exception for single-sex institutions to allow them to discriminate on the grounds of sex. However there is NO exception for gender assignment. So you could NOT refuse a transwoman with a GRC admission to a women's college, but potentially you could refuse a TW without a GRC, on the basis that it's allowable sex discrimination. As a TW w/out a GRC is in law a man, that would be allowable, presumably.
Hence the GRC might be useful in cases where sex discrimination is allowable but gender reassignment discrimination is not.
In the case of employment, the EA is usefully clear:
"The references in sub-paragraph (1) to a requirement to have a protected characteristic are to be read—
(a) in the case of gender reassignment, as references to a requirement not to be a transsexual person"
So in that case a GRC is not of any relevance either.