Alleycat I think the example you are talking about is something slightly different. That person has undergone a full transition to a trans woman. They will have paperwork, including a certificate, to show for legal purposes their gender is now female. So legally they are absolutely entitled to use women's loos and if imprisoned to serve their time in the female estate. They have been through a gruelling process of probably counselling, hormones and surgery and their need to change gender identity has been explored and assessed.
People on this thread are concerned, as am I, that the proposed new legal changes come to pass where a man can live fully as a man, the next day decide he now identifies as female and purely based on this self-identification (probably dressing accordingly and using female pronouns) and without counselling, hormones or surgery be considered as a woman in law. He still has a penis, he still has 100% male hormones, he may call himself a lesbian and continue to have sex with women, using his penis, or have sex with men using his penis (cf Tara Hudson).
He can legally go into a space where women are vulnerable or performing private acts (getting changed, using loo) and have exactly the same right as the biological women to be there. Even if he is demonstrably male (with a beard for example) and causes distress to the women using the facilities. And yet the only difference from the man he was legally classed as the day before is that he has now self-identified as a woman.
This has the potential for all manner of undesirable things to happen. It allows perverts and predators to exploit this new law and get themselves into women's loos/ prisons etc (there are real life examples of both) to assault and rape. The self-identified trans woman could be an autogynephile. Again someone who does not belong in sex segregated spaces.
It sounds absurd but every man in a prison could decide within 24 hours that they self-identified as female and as such would require transfer to the women's estate. Men have already used this tactic in real-life. If the law were to change, it would actually protect the men in this assertion and allow them to do so.
So slow's contributions aside - I honestly don't think they actually understand the nuance of this debate and think almost every poster is saying 'we hate trans women and want to treat them as sub-human'. I genuinely don't think anyone is saying that on this thread. We are saying people have the right to live and dress as they wish. But there are some scenarios where there would be dangers to women with this new legal proposal and so this idea of self-identification being enough to be classed as a woman is wrong.