Could I ask a question about the concept of 'a proportionate means of achieving a legitimate aim'?
Well, two questions really. The onus always seems to be on those arguing for single-sex spaces to demonstrate that exclusion is a proportionate means of achieving a legitimate aim. Why isn't the onus of proof ever on the claim that the protected characteristic of gender reassignment requires the inclusion (in particular situations) of people with that characteristic? I don't mean people with a GRC, I mean the wider group of people who fall under that characteristic?
The protected characteristic of gender reassignment applies to all those who are going through a process or who are considering going through that process (as well as applying to those who have completed it and received a GRC).
So here is my second question: Given that the protected characteristic is essentially defined in relation to a specified process (not to a state of being such as 'gender identity'), what are the 'legitimate aims' that might reasonably be considered to be associated with the protected characteristic?
To tease out the answer to that question, we need to look at what the process is. I know it isn't fully defined in legislation, but a key part of it is 'living as a woman' for a specified period in order to build up the evidence that the intention to transition is serious and persistent.
Importantly, from the point of view of the reassignment process, 'living as a woman' simply means building up a certain evidence base. We know that the evidence required is very slight. You are not required (for example) to prove that you have joined a lesbian dating agency or a lesbian walking group. You are not required to prove that, in any or all areas of life you are accepted as if you actually are a woman. You are not required to prove that you get changed in the women's changing rooms at the gym, or receive counselling at a women's rape refuge. You need to provide some documentary evidence, such as a utilities bill that titles you as Mrs/miss/ms, and you may need a letter from someone such as your employer.
The protected characteristic of gender reassignment is intended to pprotect people from being discriminated against on the grounds of their participation in a process that is, in fact, quite minimal. Surely that must mean that the situations in which their inclusion in single sex spaces is a proportionate means to a legitimate aim are also quite minimal? This is because the protection afforded relates to a process not an identity.
At most, the procedural requirements of 'living as a woman' seem to require employers, pubs, restaurants, etc, not to discriminate against someone because their presentation conforms to opposite-sex norms. Why would it require more than that? Why would it require random lesbians to admit you to their group? Why would it require raped women to be counselled alongside you? All that the doctor needs is a couple of bits of paper.