On Wednesday, the UK supreme court ruled that for the purposes of the Equality Act 2010, sex refers to the gender observed at birth.
Before I go any further, I'll say that I'm not a lawyer, and all this is gleaned from reading the judgment and from personal experience.
The ruling assumes sex is binary, and does not take into account intersex conditions.
When I refer to "women" and "men", the same also applies the other way around too.
The equality act generally relates to anti discrimination rules, be they for employment, organisational equality monitoring, access to services, members clubs, etc.
While transgender people are still protected against discrimination for being transgender, transgender women are now considered "biological men" for the purposes of this act and are no longer protected against discrimination for being women, regardless of whether or not they hold a gender recognition certificate or updated birth certificate.
This is not about, and does not impact access to toilets and/or changing rooms, for which there is no legal segregation, or basis for allowing or disallowing access (for now).
While this ruling has little direct impact on the lives of transgender people, it is a *massive* precedent, and has already been touted as "common sense", "transgender women are not women", a "victory for women".
In the same way that racism spiked with brexit, this will only result in an increase in abuse and attacks against women (cisgender and transgender) that do not look "womanly" enough.
The EHRC has already released guidance (soon to be a legally enforceable "statutory code of practice") to exclude access to transgender women from women's toilets, changing rooms, with the NHS "scrambling" to rewrite their policies, and the british transport police already saying strip searches of transgender women will now be done by (biological) men.
None of this is enforced on them by the act, but they're following it's lead.
The ruling also does not cover how people should be determined to be one "biological sex" or the other, or how any of this will be monitored or policed.
Are they going to attempt genital inspections? Do we all now have to carry our birth certificate around? Transgender people have been able to have corrected ID documents (passport, driving licence, etc) for decades.
The very real impact is that now *all women* will be subject to attacks and abuse based on how they look. PCOS and hair? Too tall? Too muscular? Too manly and subject to ejection.
This already happens, but this ruling is an escalation on a long line of attacks on trans people and anyone that doesn't neatly fit inside society's definition of a woman.
To rewrite the Daily Mail's headline, "Historic defeat for all women, and death of empathy".