After years of legal back and forth, the decision by the Court of Arbitration for Sport (CAS) has put to rest any doubt over Olympic 800m champion Caster Semenya's eligibility to compete in female events. She can, but only on the condition that she continues to take medication that will suppress her body's natural production of testosterone.
The decision to maintain the status quo and effectively snub Semenya plunges sport into a moral maelstrom.
People will argue persuasively that insisting that an athlete takes testosterone-suppressing medication to change a natural condition is a violation not only of individual human rights, but of its own rules. After all, since the 1970s, the vast majority of sports have affirmed and strengthened strictures on doping.
To force an athlete to change her body chemistry artificially seems monstrously hypocritical.
It also seems oddly out of sync with the zeitgeist, which has spirited to us a newish term - gender fluidity. This means that people are annexing the right to define their own sex and gender, perhaps swapping as they move through life, or even from one situation to the next. By opposing Semenya, sport confirms its commitment to the durable but outmoded binary model of two sexes at the very time when the rest of society is discarding it.
They insist sport's so-called "level-playing field" has been unbalanced. In truth, there has never been a level-playing field: success in sport is due to a variety of unequally distributed benefits, including place of birth, access to facilities, coaching and a miscellany of psychological characteristics.
The CAS appears to have been impressed by the argument that Semenya's above-normal concentrations of testosterone give her an unfair advantage over other female athletes. It's a reductive argument and one that's easy-on-the-intellect. But persuasive. Athletes who have transitioned from male-to-female are familiar with the argument - and are fighting it daily.
Semenya is not, of course, transgender, though, in many senses, the legal rejection of her appeal will reverberate. Transgender athletes across the whole spectrum of sport are under attack, particularly from female athletes who, like rivals of Semenya, feel aggrieved.
Semenya's legal battle has concluded with a decision that will have consequences as impactful and far reaching as the 1970s ruling that prohibited performance-enhancing drugs. Semenya is now the symbol of a very modern debate over gender classifications, with the pronouncement sure to have implications for intersex and transgender women across sport.
Opposition to the traditional binary model of the sexes has been under attack since the start of this century and there is no sign that attack will cease.
Gender fluidity has flooded into all areas of society and many institutions have been forced to make accommodations. The employment sector, the criminal justice system, the military and education have all changed in a way that reflects our new understanding of sex and gender - as parts of a process rather than immovable halves of a duality.
Sport refuses to change.
Had the verdict gone with Semenya, another discourse would have opened up and sport would have been challenged to change in a way that reflected the world around it.
The challenge is still there, but sport has, in a perverse way, made it harder to change.
Reaffirming faith in a sex classification system that served sport well in the 20th century is a bit like championing the internal combustion engine at a time when most of the world has recognised fossil fuel depletion and is trying to find alternatives.
Ellis Cashmore is honorary professor of sociology at Aston University, and author of the forthcoming book "Kardashian Kulture: How Celebrities Changed Life in the 21st Century" (Emerald Publishing)
Any views expressed in this opinion piece are those of the author and not of Thomson Reuters Foundation.