Over 100 human rights, sports and scientific groups, including the United Nations, have criticised the International Olympic Committee’s new gender eligibility guidelines as “a blunt and discriminatory response that is not supported by science and violates international human rights law”.

The IOC’s new guidelines, announced on Friday, mandate genetic sex tests for all athletes competing in its women’s categories, as well as blanket bans of people who identify as transgender, intersex or with sex differences.

Athletes in these categories have been allowed to compete in Olympic events since the IOC scrapped mandatory sex testing in 1999, which was deemed arbitrary, inaccurate, expensive and discriminatory.

New IOC president Kirsty Coventry reversed the organisation’s position and backflipped on its own 2021 Framework on Fairness, Inclusion, and Non-Discrimination, a policy informed by extensive consultation and research which recognised the need for evidence-based, sport-specific and rights-respecting rules.

“Mandatory genetic sex testing and rigid biological criteria as a condition for participation in the women’s category violates fundamental and universal human rights … including the right to equality, non-discrimination, dignity, privacy, and bodily autonomy,” said Professor Paula Gerber, an international human rights lawyer at Monash University.

“As several UN independent experts have noted, binary definitions of sex reinforce harmful stereotypes and erode progress toward substantive gender equality. Any testing of athletes needs to be individualised and evidence-based, not arbitrary or degrading.”

The new guidelines were developed by a committee which has not publicly shared the scientific data that the IOC claims informed their position. In a press conference on Friday, Coventry claimed all women athletes will be tested for the SRY gene, which multiple medical experts have stated is unreliable and reductive.

“The IOC’s move to mandate sex testing across the female category risks undermining both evidence-based policy and athlete wellbeing, while diverting attention from the real priorities in women’s sport,” said Dr Ada Cheung, a professor of endocrinology at the University of Melbourne.

“The best available data … shows that transgender women receiving gender-affirming hormone therapy are not meaningfully different from cisgender women in key performance-related measures such as muscle mass, strength, body composition, or cardiorespiratory fitness, and in many aspects have a disadvantage.

“This represents a return to practices that were abandoned decades ago for good reason.”

Of the tens of thousands of athletes who have participated in Olympic events since 1999, just one has identified as a transgender woman – Laurel Hubbard of New Zealand. She did not place in her event.

Athletes who are intersex or have differences of sex development, including cisgender women, will be overly affected by the new guidelines, with women of colour likely to be disproportionately targeted due to their appearance.

The guidelines do not affect community sport, but national governing bodies could follow the IOC’s lead in implementing similar tests and bans at grassroots level.

“This isn’t just about transgender or intersex athletes; this impacts every girl playing Australian sport today,” said Nikki Dryden, a human rights lawyer and former Olympic swimmer. “If these rules are adopted, it could mean that when you sign your daughter up to play sport, she may be subjected to sex testing just to participate.

“Worse, it creates a culture where someone like a coach, an official, or even another parent, feels entitled to question whether your daughter ‘looks female enough’ to belong. That is not protecting women’s sport. That is policing girls’ bodies. And once sport starts deciding which women are ‘acceptable’, no woman or girl is truly safe.

“The IOC’s new guidelines will be unlawful in Australia. Mandatory sex testing and blanket bans directly conflict with the Sex Discrimination Act, our sporting National Integrity Framework, and our safeguarding obligations to children.

“Moving towards exclusionary, invasive rules is not only unnecessary, it is a step back over 25 years that exposes athletes and organisations to serious legal and integrity risks.”

Australian Olympic Committee president Ian Chesterman said he supported the new guidelines, and offered affected athletes counselling and support.

“Without doubt, this is a challenging and complex subject and at the AOC we approach it with empathy and understanding,” Chesterman said.

“This decision provides clarity for elite female athletes who compete at the highest level and demonstrates a commitment to fairness, safety and integrity in Olympic competition, all of which are fundamental principles of the Olympic movement.”

Australia’s chef de mission for the 2028 Games in Los Angeles, Anna Meares, said she commended the IOC for “taking the lead” on the issue.

“The IOC ruling today protects female athletes at the highest level of competition, ensuring it remains safe and fair,” said Meares. “I also know the pain this decision will cause some athletes and I empathise with them.

“This is about integrity on the Olympic field of play. Female athletes know that when they compete it will be fair, it will be safe.”

The AOC said it will now take some time to work with the IOC and member sports to fully understand the workings of the new policy.