I posted this article already. Here is the important bit
One of the main reforms proposed is that anyone should be able to be formally recognised as a member of the other sex purely on the basis of self-identification. Therefore, the sole criterion for determining that a person is a woman would be that person’s belief (or stated belief) that they are a woman. Anyone who wants to be a woman would have to be viewed as one.
The effect of this proposal becoming law would be to erode the very concept of woman. It will erase women’s lived experiences, and undermine women’s rights. Being a woman is about sex and biology, in that our bodies determine so much of our experience, and also about the way we are constructed socially, which also helps determine our lived experiences. It is not about how a person feels or what they claim to feel.
Self-identification will allow anyone to access women’s spaces at any time, having self-proclaimed that they are a woman. This is problematic for women accessing women’s spaces and services whose lived experiences (such as surviving sexual violence) or protected characteristics (such as religion that requires sex-segregation for certain activities) make it essential that women’s spaces remain sex-segregated.
Self-identification is also open to abuse by men seeking to access women’s spaces and women’s bodies. We are already seeing people who were born and still live and present as men claiming that they are trans-women in order to gain access to women’s spaces, including convicted sex offenders demanding to be housed in women’s prisons; individuals videoing women and girls naked in women’s changing rooms; and individuals seeking to join all-women candidate lists in local or national elections. Allowing self-identification of trans people will enable and embolden these types of activities.