The 2028 Los Angeles Olympics will feature a women’s category unlike any in recent Games: mandatory genetic testing for every athlete, and exclusion for anyone who has experienced male sex development.

The International Olympic Committee announced Thursday that eligibility for all women’s Olympic events will be determined by a one-time screening for the SRY gene — a segment of DNA typically found on the Y chromosome that initiates male development. Athletes who test positive, including transgender women and those with certain differences in sex development (DSD), will be barred from female competition.

The policy represents a sharp reversal from 2021, when the IOC adopted a framework emphasizing inclusion and left eligibility decisions to individual sports federations. Now, a single universal standard applies across all Olympic sports.

“At the Olympic Games, even the smallest margins can be the difference between victory and defeat,” said IOC President Kirsty Coventry. “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.”

Who’s Affected

The rules, which take effect for Los Angeles and are not retroactive, bar transgender women, athletes with DSD conditions who are sensitive to testosterone, and virtually anyone who screens positive for the SRY gene.

There is one narrow exception: athletes with Complete Androgen Insensitivity Syndrome (CAIS), a rare condition where the body cannot process testosterone. Because they derive no performance benefit from androgens, they remain eligible for women’s competition.

The IOC says the screening — conducted via saliva, cheek swab, or blood sample — will be a “once-in-a-lifetime” test. Athletes who screen negative permanently satisfy eligibility criteria.

A Decade of Reversals

The announcement ends years of IOC efforts to avoid a blanket policy. After abandoning sex verification tests in 1999 following controversies over false positives and privacy concerns, the IOC allowed federations to set their own rules. The 2021 framework was the high-water mark of that approach, emphasizing inclusion and leaving eligibility decisions to individual sports federations.

But that framework was already strained. The Paris 2024 Olympics faced intense scrutiny when boxers Imane Khelif of Algeria and Lin Yu-ting of Taiwan won gold medals a year after being disqualified from the World Championships for allegedly failing eligibility tests. The IOC defended their participation, noting both were identified as female on their passports — but the controversy was immediate and sustained.

Coventry, who made reform a priority upon taking office last year, said the IOC consulted more than 1,100 athletes through surveys and interviews. The working group included specialists in sports science, endocrinology, transgender medicine, and ethics.

The Science and Its Critics

The IOC concluded that male sex provides performance advantages ranging from 10 to 12 percent in endurance and speed-related sports to more than 100 percent in strength-based events — advantages established through testosterone exposure during three critical periods: in utero, during infancy, and beginning in puberty.

Not all experts agree that SRY screening is the right tool to address this. Dr. Andrew Sinclair, the professor who first identified the SRY gene, has argued that using it to establish biological sex is fundamentally flawed.

“Biological sex is much more complex, with chromosomal, gonadal, hormonal and secondary sex characteristics all playing a role,” Sinclair wrote in August 2025. “Using SRY to establish biological sex is wrong because all it tells you is whether or not the gene is present.”

More than 80 human rights and sports advocacy organizations have opposed the policy, citing concerns about privacy, the potential for false positives, and psychological harm to athletes subjected to scrutiny over natural biological variations.

The Human Cost

For athletes caught in this shifting landscape, the human dimension is inseparable from the competitive one.

Caster Semenya, the two-time Olympic champion in the 800 meters, has spent nearly a decade fighting eligibility restrictions. Her DSD condition means she has XY chromosomes. Under the new policy, she would not have been eligible for the races that made her an Olympic champion.

The IOC says its policy “is not a judgement on, and does not question, the athlete’s legal sex or gender identity.” But for athletes like Semenya — who has always identified as a woman and never transitioned — that distinction may offer little comfort. The rules she once competed under have changed, retroactively rendering her victories contested territory.

What Comes Next

The policy applies only to IOC events, not recreational sports. But the IOC’s decision will pressure other governing bodies to follow suit. World Athletics and World Aquatics have already implemented similar restrictions; now every Olympic sport faces pressure to align.

In the United States, the new rules align with an executive order from President Donald Trump barring transgender athletes from women’s sports. The White House quickly claimed credit, with Press Secretary Karoline Leavitt writing: “President Trump’s Executive Order protecting women’s sports made this happen!”

Whether the policy survives legal challenges remains to be seen. What’s clear is that the era of fragmented eligibility rules is over. The IOC has bet that fairness in women’s sports requires a single, science-based standard — even if that standard draws sharp lines around biological categories that nature itself does not always respect.

For athletes who fall on the wrong side of those lines, the Olympic dream is effectively closed.