This is really positive news for women in the UK. Up until now there's been considerable uncertainty over exactly who, by law, can have access to nominally single-sex spaces. The Supreme Court ruling clarifies this, and probably the most immediate impact of this will be on tribunal cases currently in progress.

There are two that have been widely publicized, involving female nurses working for NHS hospitals who've objected to male colleagues being allowed by hospital management to use female changing rooms on the basis of these males calling themselves women. This ruling means that the tribunals can now be expected to judge this policy, and the punitive actions of the NHS against female employees who objected, to be incompatible with the law.

At the same time the ruling clarifies that the law still protects people who have gender identity self-beliefs from harassment and discrimination, which is also good news and a sensible middle ground for how society should regard this phenomenon.