A new rule requiring all female athletes in world ranking competitions to undergo a one-time genetic test has come into force this week.

The measure, announced by World Athletics, is designed to safeguard the women’s category by checking for the presence of the SRY gene, which is linked to male development. Supporters see the move as a long overdue step towards fairness, while critics say it raises scientific, legal, and ethical concerns.

What The New Test Looks For

The test searches for the SRY gene, a section of the Y chromosome that triggers male development during puberty. When present, it typically leads to the formation of testes and increased testosterone levels, which in turn influence muscle mass and strength. Athletes who have XX chromosomes, and therefore no SRY gene, fall within the female category.

Complications arise for athletes born with differences in sex development (DSD). Some individuals may be registered as female at birth and raised as such, but still have XY chromosomes. In these cases, the test is intended to clarify eligibility. World Athletics says anyone who tests positive will be further assessed, and only those with conditions like complete androgen insensitivity syndrome (CAIS), which prevents the body from using testosterone, will remain eligible to compete as women.

The introduction of such a clear-cut rule has also invited comparisons with other regulated systems. Just as punters look at the list of betting exchange sites before placing wagers, ensuring they understand the rules of each platform, governing bodies are now applying a fixed measure to decide who qualifies for women’s competition. The point in both cases is the same: outcomes must be trusted, and confidence relies on transparent rules.

How The Testing Will Be Done

Each athlete only needs to take the test once. The process involves either a cheek swab or a small blood sample, which is submitted to their national federation. So far, more than nine out of ten athletes set to compete at the next World Championships have already completed the process, with the remaining tests due shortly before competition.

There have been some hurdles. Athletes from France and Norway, for example, had to travel abroad because domestic law prevents genetic testing outside of medical contexts. In Canada, a technical issue meant several samples had to be redone. Despite these complications, Lord Coe, president of World Athletics, insists that athletes have shown broad support, arguing the rule gives reassurance that female competition remains protected.

Why Now?

The debate over gender and eligibility has shadowed athletics for more than a decade. It first drew worldwide attention in 2009 when South African runner Caster Semenya stormed to victory in the 800m at the World Championships. Semenya was later identified as having a DSD condition, prompting years of argument over whether existing rules were enough to ensure fairness.

Since then, World Athletics has steadily tightened its stance. Initial attempts required DSD athletes to lower their testosterone levels for middle-distance events. Later changes extended those requirements across all track and field competitions. In 2023, transgender women who had gone through male puberty were excluded from women’s events altogether. The new SRY gene test is the latest escalation, introduced after research suggested testosterone reduction did not completely remove the advantage of male puberty.

Beyond Athletics

Other sports are already taking notice. World Boxing has adopted a similar rule, insisting athletes in female categories take the same test. This comes after the controversy at the 2024 Paris Olympics, when boxers Imane Khelif and Lin Yu-ting won gold despite having previously failed eligibility checks by another governing body. That episode fuelled calls for consistency across international sport.

The International Olympic Committee has so far resisted adopting blanket rules, citing concerns about fairness and inclusion. However, with the Los Angeles 2028 Games drawing closer, pressure is mounting for a unified standard. New IOC president Kirsty Coventry has said protecting women’s sport is a priority, while US President Donald Trump has already pledged that some form of sex testing will be required at LA 2028.

Divided Opinions

Not everyone agrees with the approach. Some scientists argue the test is too simplistic, pointing out that the presence of the SRY gene alone does not account for the wide range of natural variations in sex development. Andrew Sinclair, the researcher who first identified the SRY gene in 1990, has been outspoken in saying mandatory use of it is flawed. Others warn of potential false positives if samples are contaminated.

There are also concerns about privacy. Former Olympian Madeleine Pape, now a sociologist, has highlighted the risk of athletes being inadvertently “outed” with medical details they may not have known about. American middle-distance runner Nikki Hiltz, who identifies as transgender and non-binary, has also criticised the rule, saying resources would be better directed at anti-doping measures and athlete welfare.

World Athletics insists that privacy is being handled carefully. Results are uploaded to a secure system, and athletes can request retests or challenge findings through the Court of Arbitration for Sport. The organisation also argues that this method is more humane than requiring DSD athletes to alter their natural hormone levels, which has previously attracted heavy criticism.

Could Legal Action Follow?

Legal challenges are almost certain. Semenya herself has been in and out of court for years contesting earlier regulations. Although she lost key appeals, the European Court of Human Rights ruled in 2025 that her right to a fair hearing had been violated during part of that process. That decision could encourage new appeals against the latest rule.

Lord Coe has expressed confidence that the testing requirement will stand, emphasising that human rights obligations have been considered carefully. Supporters argue the measure is necessary to ensure fair competition for female athletes. Detractors counter that it risks discrimination and relies on incomplete science.

For now, the rule is in place and already reshaping the women’s category in athletics. Whether it brings clarity or triggers another round of disputes remains to be seen, but its impact will be felt well beyond the track.