Rowling tweeted support for Maya Forstater, the expression of whose views constitute harassment and victimisation of transwomen and discrimination against them.
Rowling spoke out against a Devex article for using the phrase "people who menstruate" instead of "women". She stated that denying the reality of biological sex erases the experiences of women worldwide and eliminates the possibility of same-sex attraction. Harassment etc, as above.
Rowling published an essay on her personal website in 2020 in which she revealed that she was a survivor of domestic abuse and sexual assault, and stated that "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". This conflates TW with male predators.
Rowling argues that adults are promoting an ideology that is harmful to children, and claims the term cisgender is "ideological language signifying belief in the unfalsifiable concept of gender identity." Thus denying the existence of trans people and fulminating against healthcare for them.
She is a hypocrite who claims that her beliefs arise out of a sincere concern for transgender people, and in particular, young transgender men.
Rowling opposes legislation to advance gender self-recognition and enable transition without a medical diagnosis.
She also voiced opposition to the Scottish Gender Recognition Reform Bill, aimed at allowing transgender people to change their legal gender more easily and subsequently she donated £70,000 to the legal challenge brought by For Women Scotland against the Scottish Ministers in the UK Supreme Court, which, on 16 April 2025, ruled that the legal definition of a woman in the UK Equality Act 2010 is based on biological sex.
In response to Edinburgh's rape crisis centre being run by a trans woman, Rowling established a sexual assault crisis centre, Beira's Place in December 2022 that excludes trans women.
In response to a fan praising this decision, Rowling tweeted "Merry Terfmas".
Rowling has also expressed her opposition to the Hate Crime and Public Order (Scotland) Act 2021, and when this went into effect in April 2024, she deliberately misgendered several transgender women to challenge the new law.
TLDR
She doesn't believe that humans can change sex.