In its recent judgement on “biological sex”, the Supreme Court avoided defining what “biological sex” is. It says it is “commonly understood”, however the phrase does not appear in most leading dictionaries.
This is of particular interest to me. As an intersex person, I am not, in UK legal terms, transgender, and I am comfortable presenting as a man in many contexts. I typically use men’s loos, and play men’s sports. But I would not call myself “biologically male”, except in some very peculiar contexts. Reading the recently released EHRC guidance, this seems to imply that I should not use men’s loos or play men’s sports. Does it?
Wiktionary, the only dictionary I have to hand that attempts to define the phrase, defines biological sex as “assigned sex”, that is, the documented sex one receives at birth from a brief identification of one’s observable sex characteristics. Unfortunately, this is clearly not what the Supreme Court intended, as it does not mention birth certificates or medical identification at all, and it explicitly distinguishes between “biological sex” and “certificated sex”. It also wouldn’t help intersex people, who have all sorts of fantastic claims made on their birth certificates.
It also cannot refer to how “biological sex” is sometimes used in genetics, that is, to chromosomal sex. Chromosomal sex is almost never observed in humans, and when it is, it is observed to be only one of many factors that contributes to the meat (as it were) of what is observable “sex”.
One must infer, therefore, that the UK Supreme Court intended to define biological sex as “some observable sex characteristic or characteristics at birth, which is typically recorded on a birth certificate”. And perhaps this is what they mean by “commonly understood” – that is, sex at birth is what is observable at birth to some common analysis.
Now, nobody is a woman or man at birth – these are terms we use for adults – and trans people have all sorts of biological and biochemical characteristics, depending on their medical transition or absence thereof. Unless the Court imagined transgender people as springing like Athena from the mind of a god, one must therefore further infer that what they mean by “biological man” is “a person who was identifiable as male at birth due to some bundle of biological characteristics”, and the same for “woman” and “female”.