New Zealand was one of the nations that voted in favour of world swimming's ban on transgender athletes competing in women's elite racing.
The policy was confirmed by FINA member federations at its general congress at Budapest, Hungary, with overwhelming 71-percent support.
But the decision has divided communities both here and around the world, and has other sporting bodies watching with great interest.
In a landmark moment for transgender women in sport, American swimmer Lia Thomas made history when she became the first trans-athlete to win the 500 yard freestyle at the national collegiate championships in March.
"It means the world to be here, with two of my best friends and teammates, and be able to compete," said Thomas.
But ultimately, her achievements have fast-tracked the debate over transgender athletes competing in elite women's sport.
FINA member federations - including New Zealand - have voted to ban them from doing so, once they've gone through male puberty.
Former Olympic swimmer and retired sports medicine professor Dr David Gerrard was at the congress, and voted on behalf of Aquatics NZ.
"The evidence is overwhelming," said Gerrard. "It was an easy decision - you only have to look as far as Laurel Hubbard."
When Hubbard was included in the NZ weightlifting team for last year's Tokyo Games, Gerrard was among a group of former NZ Olympians that lobbied against transgender athletes competing against women.
This week, physicians, exercise scientists, human rights lawyers and current female swimmers were all given the chance to have their say.
Bruce Jenner, who won men's decathlon gold at the 1976 Montreal Olympics and later transitioned to Caitlyn Jenner, supports the move.
"What's fair is fair," she tweeted. "If you go through male puberty, you should not be able to take medals away from females, period."
Others in the trans community disagree.
"They're looking for evidence that trans-women are a threat to other women," said Gender Minorities Aotearoa spokesperson Ahi Wi-Hongi.
Thomas also disputes claims she has an unfair biological edge that ruins the integrity of women's sport.
"I'm a swimmer at heart," she said. "It's what I love to do and it's part of who I am, and I don't want to give that up.
But while FINA's decision ultimately brings an end to competing as a female at the Paris, Thomas' Olympic dream may not be over, with the governing body looking at establishing an "open" category.