In March 2019, Forstater criticised the
Minister for Women and Equalities,
Penny Mordaunt, for her
Mumsnet webchat on
International Women's Day. Mordaunt received many questions regarding women and transgender people; she did not answer them. Forstater wrote in
The Independent that Mordaunt had asked for "discussions on the topic of sex and gender identity to take place in a 'climate of respect, empathy and understanding', but when faced with a group of mothers asking respectful and carefully researched questions, she ducked and ran". In late-May 2021, Forstater commented under an article published in
The BMJ that she believed
gender identity should not be used in the collection of sex data for medical matters. The authors of the article responded that she had "misrepresented" their point, as they were not advocating that gender identity be used as a proxy for sex, but rather that "relevant and accurate information about a person's body and health needs cannot reliably be assumed with sex assigned at birth data." In their response, the article's authors emphasised that "many
cisgender and transgender people have the ability to become pregnant". Forstater's experiences are referred to in
Kathleen Stock's book
Material Girls: Why Reality Matters for Feminism in the context of how the charity
Stonewall might influence court rulings. In May 2021, Forstater was among 41 signatories to an
open letter calling on the
Equality and Human Rights Commission (EHRC) to end its membership of the Stonewall
Diversity Champions scheme, and on the
Committee on Standards in Public Life to oversee a review of "the role of Stonewall in public life" and its "influence and control" over the
Human Resources policies of public institutions. Later that month, the EHRC withdrew its membership of the Stonewall scheme. Also in 2021,
Baroness Falkner of Margravine, the new EHRC chair, mentioned Forstater in her first interview after taking office, citing her as someone who had faced abuse for her views and stating that "a lot of people would find [it] an entirely reasonable belief" that "people who self identify as a different sex are not the different sex that they self identify." Forstater was an invited speaker to a
University of Cambridge student event on the topic of
freedom of speech and belief. In December 2021, Forstater received an apology from
The Scout Association after a complaint was made against her, and published the text of the apology on her website. Forstater had described the complaint as "
vexatious".
Support from J. K. Rowling In December 2019, author
J. K. Rowling tweeted #IStandWithMaya in support of Forstater's legal case. The two first met in person at a lunch in April 2022 hosted by Rowling for gender-critical activists. Forstater described the occasion as "emotional" and praised Rowling as a "source of strength".
Sex Matters In 2021, Forstater became a founding officer of the
gender-critical organization
Sex Matters alongside co-founders Rebecca Bull, Naomi Cunningham, and Emma Hilton. The
lobbying group opposes
transgender rights and has been involved in several legal cases against
trans-inclusive legislation in the United Kingdom. In April 2025, Forstater, as Chief Executive of Sex Matters welcomed the Supreme Court ruling that "the terms woman and sex in the Equality Act 2010 refer to a biological woman and biological sex" in the case
For Women Scotland Ltd v The Scottish Ministers, stating "the protected characteristic of sex - male and female - refers to reality, not to paperwork." ==Personal life==