Is it right to require someone to take drugs to compete in international sports? On Wednesday the Swiss-based Court of Arbitration for Sport said yes, ruling that the world’s top middle-distance runner, South African Caster Semenya, must suppress her naturally high testosterone levels to run in women’s races.

The court, it must be said, didn’t appear overly pleased with its own decision. It fully admitted that the rule was discriminatory but said the discrimination was necessary to uphold the integrity of women’s events.

The ruling on one hand evoked outrage. “Shouldn’t Semenya’s physical abilities be celebrated the same way as Usain Bolt’s height and Michael Phelps’s wingspan are?” a BBC commentator argued. Yet the ruling is also a natural outgrowth of another trend: the increasing emphasis on biology in elite sports.

If testosterone levels or red-blood-cell counts are the ultimate arbiter of athletic achievement, then the discrimination against Ms. Semenya would seem to have some basis. But is that all there is to sport? Ms. Semenya is also just a woman who loves to run fast and who has become an inspiration in her homeland.

As this case shows, these issues can be difficult and nuanced. But the years ahead point to them becoming only more poignant.

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