The Single and Separate Sex Exceptions in the Equality Act 2010 are the bit of UK law which allows single sex services. They are tucked away in Schedule 3, Part 7, Paragraphs 26 and 27 and it is sometimes said they are ‘rarely used’, or that service providers have to choose to use them in exceptional circumstances. This is a myth and a misunderstanding.
Single sex spaces, such as women’s and men’s changing rooms, toilets, dormitories, hospital wards, and women’s refuges are not natural features of the landscape; like mountains or rivers to be explored. They are created through plans, policies and rules – service providers create a single sex space by adopting a policy that an area is only open to people of one sex (and in some cases their accompanying small children). In other word they discriminate. They communicate the discriminatory policy with words and signs.

When you do that they are using the single sex exceptions in the Equality Act.
That is it.
A service provider doesn’t have to do anything else to use an exception (although it is always a good idea to consider the reason for policies, and write them down).
What the exceptions in the Act do is allow sex discrimination in situations where sex discrimination is justified. If challenged (including in court) the service provider can say the discriminatory policy, as communicated by the sign, is objectively justified and allowed by the Equality Act.
Using the exceptions does not mean service providers have to make a separate objective justification every time the policy is used (i.e. every time a person is excluded from sharing an intimate space with members of the opposite sex ; usually people just comply with the sign).
“But these are not ‘single sex services’ they are ‘single gender'”
Some people make an argument that despite such single sex services being an everyday feature of of life — in schools, colleges, shopping centres, gyms, parks up and down the country — the Equality Act exceptions are nevertheless rarely used because these are not in fact single sex services, but something else: “single gender services”.
Thus they say these spaces are not covered by the Equality Act at all.
This is nonsense on stilts.
Firstly the kinds of services that are provided on a single sex basis are exactly the kinds of situations that are covered by the criteria set out in Schedule 3 Part 7 of the Equality Act and mentioned in the explanatory notes.
Secondly, most people understand the words man and woman, male and female and the associated symbols to mean a person’s sex. You might say “gender”, but most people will answer with their sex, and not realise you were meaning some other concept (and it is never clear what is meant by gender). They could well object to sharing an intimate space with a person of the opposite sex, having not given their consent.
Thirdly the Equality Act also includes “discrimination by perception”. One meaning of gender is “the sex that other people perceive you to be”. Thus if a service provider were to try to justify a discriminatory policy by saying the sign doesn’t mean sex but “the sex you are perceived to be by others” (and you call that ‘gender’) they would still be discriminating on the basis of the protected characteristic of sex. They would still be relying on the single sex exceptions (an employer couldn’t for example have a policy of only hiring men for senior positions and get away with saying that it is based on their “gender” (perceived sex), and therefore it is not sex discrimination).
Finally the Equality Act also includes indirect discrimination. That is, applying a rule which applies equally to everyone but which affects certain groups differently. So if a service provider writes down that their policy is to provide ‘gender’ segregated spaces based on internal feelings of “gender identity” and not sex, they are still likely to be discriminating on the basis of sex since most people without a degree in gender studies will still understand that the sign means their sex. This would be like a having a policy of saying you won’t employ people called Singh and arguing that it is definitely not religious or race discrimination.
What these word games, and arguments that “single sex services are uncommon”, or are “not really single sex services” are designed to do is to distract from the reason for single sex services in the first place.
The most common reason, which is allowed for in the Equality Act at Schedule 3, Paragraph 27 (6), is bodily privacy ” when a person of one sex might reasonably object to the presence of a person of the opposite sex.”
Single sex services are by their nature not for everyone, and people who don’t want to share with others of the same sex can usually be accommodated in unisex facilities. What they cannot do is demand to share intimate spaces with members of the opposite sex without their consent.
Protecting everyone’s rights and dignity means being clear about whether a service is single sex or mixed sex. This requires clear, unambiguous rules, not word games designed to confuse.