A woman who lost her job after saying that people cannot change their biological sex has lost an employment tribunal.
Maya Forstater, 45, did not have her contract renewed after posting a series of tweets questioning government plans to let people declare their own gender.
Ms Forstater believes trans women holding certificates that recognise their transgender identity cannot describe themselves as women.
But that view is "not worthy of respect in a democratic society", a judge said.
Ms Forstater, who had worked as a tax expert at the think tank Center for Global Development, was not entitled to ignore the rights of a transgender person and the "enormous pain that can be caused by misgendering", employment judge James Tayler said.
Ms Forstater was "absolutist" in her view, he concluded in a 26-page judgement.
"It is a core component of her belief that she will refer to a person by the sex she considered appropriate even if it violates their dignity and/or creates an intimidating, hostile, degrading, humiliating or offensive environment," he continued.
"The approach is not worthy of respect in a democratic society."
Ms Forstater had argued "framing the question of transgender inclusion as an argument that male people should be allowed into women's spaces discounts women's rights to privacy and is fundamentally illiberal (it is like forcing Jewish people to eat pork)".
Author JK Rowling is among people who have come out in support of Ms Forstater.
Dress however you please.— J.K. Rowling (@jk_rowling) December 19, 2019
Call yourself whatever you like.
Sleep with any consenting adult who’ll have you.
Live your best life in peace and security.
But force women out of their jobs for stating that sex is real? #IStandWithMaya #ThisIsNotADrill
Ms Forstater, who raised more than £85,000 through crowdfunding to pay her legal bills, said in response that she was "blown away by the support and interest in her case".
"All I ever wanted on this was for people to be able to talk about the policy questions around sex and gender identity in a normal, open, democratic way".
Gender identity is a matter of enormous public interest and there are a range of different and strongly held views.
Some will regard this judgment as preventing people from expressing their honestly held belief that a person born in a male body cannot become a woman, without the threat of being dismissed from their job for doing so.
Others will see it as much needed protection for the rights of those who wish to identify as the gender they feel themselves to be.
Employment tribunal rulings are not binding legal precedents, but they do have weight, and this ruling could deter others who share Maya Forstater's views from bringing such cases in the future.
Ms Forstater's solicitor Peter Daly, of Slater and Gordon, said: "The significance of this judgment should not be downplayed.
"Had our client been successful, she would have established in law protection for people - on any side of this debate - to express their beliefs without fear of being discriminated against."