"I REFUSE TO BOW DOWN"
Rowling said that she believed most trans people not only posed zero threat to others but were vulnerable, and that they deserved protection.
At the same time, she said, she did not want girls and women to be less safe, and she gave some examples of where she thought demands by trans people were dangerous to women.
"When you throw open the doors of bathrooms and changing rooms to any man who believes or feels he's a woman ... then you open the door to any and all men who wish to come inside."
Describing some of the abuse she had received -- including being told she was "literally killing people with your hate" and being compared with Voldemort, the villain of the Potter series, Rowling said many women were terrified by trans activists.
"I refuse to bow down to a movement that I believe is doing demonstrable harm in seeking to erode 'woman' as a political and biological class and offering cover to predators like few before it," she said.
Addressing the specific issue of the use of phrases like "people who menstruate" as a way of including trans women, Rowling said such language was demeaning to many women.
"I understand why trans activists consider this language to be appropriate and kind, but for those of us who’ve had degrading slurs spat at us by violent men, it’s not neutral, it’s hostile and alienating."
Rowling said she had not written the essay in the hope that anyone would get out a violin for her, and that she considered herself extraordinarily fortunate.
"I’ve only mentioned my past because, like every other human being on this planet, I have a complex back-story, which shapes my fears, my interests and my opinions. I never forget that inner complexity when I’m creating a fictional character and I certainly never forget it when it comes to trans people.
"All I’m asking – all I want – is for similar empathy, similar understanding, to be extended to the many millions of women whose sole crime is wanting their concerns to be heard without receiving threats and abuse."