By Nana Karikari, Senior Global Affairs Correspondent
The International Olympic Committee’s return to mandatory sex testing represents more than a policy shift. It is a fundamental realignment of the Olympic movement toward a biological definition of fairness that could reshape elite sport for a generation. Announced on Thursday, this landmark policy bars transgender women from female categories and marks the definitive end of a decades-long experiment with inclusive, testosterone-based eligibility.
Under the leadership of President Kirsty Coventry, the organization will now mandate one-time genetic testing for all female category participants—a rigid, centralized departure from the I.O.C.’s 2021 decentralized framework. Set to take effect at the Los Angeles 2028 Summer Games, this pivot reflects a growing institutional urgency to insulate the Olympic brand from the polarizing “fairness vs. inclusion” debate that upended the Paris 2024 Games. By codifying biological sex as the sole entry point and aligning with tightening global political trends, the committee has signaled a strategic retreat from previous inclusion models, setting the stage for a high-stakes legal and scientific confrontation.
Genetic Testing and Implementation
The new eligibility criteria center on a one-time genetic test. This screening mirrors protocols utilized in international track and field. Officials will collect samples via saliva, cheek swabs, or blood. The expert group selected this method as the “most accurate and least intrusive” way to screen for the SRY gene. This DNA segment typically initiates male sex development and indicates the presence of testes. While the I.O.C. maintains this provides a clear biological standard, critics and medical experts question the reliability of such reductive measures.
The policy also addresses athletes with differences of sex development (DSD). These individuals possess XY chromosomes and elevated natural testosterone. They are now largely excluded from women’s events. However, the ruling does not restrict transgender men from competing in the female category. It also excludes recreational sports. The I.O.C. clarified that DSD athletes may still compete in male or mixed-gender categories. Critically, the policy is not retroactive. It will not affect results or records from previous Games.
Quantifying the Performance Gap
The IOC’s 10-page policy document details specific research regarding male biological advantages, citing three distinct testosterone peaks: in utero, during infancy, and at puberty. These peaks create sex-based advantages in strength and endurance that the committee argues are insurmountable. According to the document, the male performance advantage is approximately 10-12% in most running and swimming events, growing to 20% in jumping and throwing. In “explosive power” or “punching sports,” the advantage can exceed 100%. These figures serve as the IOC’s primary defense against claims of discrimination.
Leadership and the Push for Fairness
President Kirsty Coventry, the first woman to lead the I.O.C., framed the decision as a defense of the female category. During her campaign, she emphasized the need to maintain competitive integrity.
“At the Olympic Games, even the smallest margins can be the difference between victory and defeat,” Ms. Coventry said. “So, it is absolutely clear that it would not be fair for biological males to compete in the female category. In addition, in some sports it would simply not be safe.”
Coventry asserted that the policy is based on science and led by medical experts. She explicitly decoupled the ruling from external political pressures. “This was a priority for me way before President Trump came into his second term,” Coventry said. She added that there was no pressure from outside the Olympic Movement.
Scientific and Human Rights Contention
The scientific community remains divided over the I.O.C.’s internal findings. A review led by Dr. Jane Thornton suggested that athletes with male sexual markers retain
physical advantages even after testosterone suppression. However, this data has not been made public, leading to accusations of a lack of transparency. The I.O.C. stated its research included “in-depth individual interviews with impacted athletes from around the world” to inform the final document.
The decision has created a complex legal paradox within the organization. While the new eligibility rules restrict participation, the Olympic Charter explicitly states that access to play sport is a fundamental human right. Human rights advocates have voiced sharp opposition to the shift. Professor Paula Gerber noted that “Mandatory genetic sex testing and rigid biological criteria… violates fundamental and universal human rights.”
Impact on Athletes and Diversity
The reintroduction of sex testing has sparked fears regarding the policing of women’s bodies, particularly for athletes of color. Historically, athletes like South African runner Caster Semenya have faced intense scrutiny due to natural biological variations. Semenya, who lost a 2019 legal challenge regarding testosterone limits, was among nine African athletes to warn of “cruel and degrading treatment” resulting from such regulations.
“I have carried this weight. So have other women of color who deserved better from sport,” Ms. Semenya said. She described the new rules as a regression, stating, “Reintroducing genetic screening is not progress — it is walking backward. This is just exclusion with a new name.”
The Shift from Paris to Los Angeles
The ruling marks a sharp U-turn from the IOC’s 2021 framework, which encouraged inclusion and left specific rules to individual federations. This decentralization led to a flashpoint at the Paris 2024 Olympics, where the participation of boxers Imane Khelif and Lin Yu-ting sparked global debate. While Imane Khelif has expressed intent to undergo testing for 2028, and Lin Yu-ting was recently cleared by World Boxing after passing a gene test, the IOC’s new blanket policy aims to codify these requirements across all sports. It effectively ends the era of the 2021 policy, which permitted transgender women to compete if they maintained reduced testosterone levels.
Alignment with U.S. Executive Policy
The I.O.C. policy aligns closely with President Trump’s “Keeping Men Out of Women’s Sports” executive order signed in February 2025. The White House, which had previously threatened to deny visas to certain athletes for the L.A. Games and rescind
funds from compliant organizations, welcomed the decision. White House spokesman Davis Ingle called the alignment “common sense and long overdue.” Consequently, the U.S. Olympic body has updated its guidance to ensure national sports organizations comply with these new standards ahead of 2028.
Global Support and Legal Challenges
Despite the controversy, the decision has found significant support among sports officials and political leaders. Australian Olympic Committee President Ian Chesterman cited a commitment to fairness and integrity, while Australian chef de mission Anna Meares added that the ruling “protects female athletes at the highest level of competition.”
However, legal hurdles remain. In countries like France, privacy laws restrict genetic testing for gender determination, potentially forcing athletes to seek screening in third countries. Ms. Coventry acknowledged that the policy will likely face challenges at the Court of Arbitration for Sport, the world’s highest sporting tribunal. Athletes such as Dutee Chand and Semenya have used this court to challenge previous versions of eligibility rules, and any new appeal would likely focus on the unpublished science underpinning the IOC’s research.
A Defining Mandate for the Olympic Future
As the global sporting community moves toward 2028, the I.O.C. finds itself at the center of a profound cultural and biological debate. By prioritizing a specific definition of biological fairness and physical safety, the committee has provided the clarity long sought by many governing bodies and female athletes. Yet, the cost of this clarity remains a subject of intense scrutiny, as the organization must now navigate the legal, ethical, and human consequences of a policy that fundamentally alters the inclusive aspirations of the Olympic movement.
