[quote SpindelWhorl]@nauticant, I've never really understood the Taylor v Jaguar decision tbh.[/quote]
If you look at the facts in the case, it's quite clear cut.
A male employee adopts a feminine-coded appearance. Gets harassed and bullied because of that appearance. Some of the remarks seem harmless, but if you look at the whole, there's a pattern of behaviour directed at that employee by colleagues that crossed the line. The employer failed to act even though they should have protected the employee and stopped the behaviour. That's why the employee won at the tribunal.
The protected characteristic of gender reassignment applies here, regardless of the employee's self-identification as non-binary rather than as a woman, because the protected characteristic of gender reassignment says:
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.
It doesn't mention identity, it doesn't talk about the protected characteristic only applying if you call yourself by a particular identity term. The protected characteristic only refers to a process.
And the employee in that case is covered, because that process of transitioning was undeniably and very publicly happening.
I don't think the jubilant reactions by trans rights organisations to the judgement were justified - in my view the law is clear, where you have evidence of an actual transition - the very process referred to in the law - happening, it's straightforward. Obviously the employer was always going to claim that the employee wasn't covered by the protected characteristic of gender reassignment, because that's what employers in tribunals will do - use every tool at their disposal.
The case would have been far more difficult if there was no transition at all. How do you prove intention to undergo a process and how do you prove others knew about that intention, and then treated you unfairly because they knew, in the absence of any outward evidence of transition?
But this case was not hampered by that problem.
HTH