The sporting world tries to balance inclusion, fairness and safety, and the latest federation to ban trans athletes is rugby.
The International Rugby League said it considered several relevant developments in world sport when making the decision, including the International Olympic Committee's recent guidance that each sport should decide their policies governing the inclusion of trans athletes.
Trans athletes will not be allowed to compete in the Women's Rugby World Cup.
In explaining its decision, the IRL said it had to balance the right to participate with the perceived risk to other participants.
The decision follows a vote on Sunday by the governing body of swimming to bar the majority of trans women from competing in elite events.
On Monday, Lord Sebastian Coe, president of World athletics, said that fairness is non-negotiable and that track and field could suit trans athletes.
Soccer's international governing body said it is also looking at its policies.
The inclusion of trans people, especially trans women, in sport is divisive and has troubled sporting federations for a long time. Rugby league and swimming are likely to be the front runners for many new policies because of the IOC recommendation. Not all policies will bar trans women from competing and cycling's international governing body tightened its eligibility criteria but did not bar athletes.
The success of Lia Thomas, a trans woman and former University of Pennsylvania swimmer, has sparked debate over trans inclusion in sport.
Critics argue that trans participation is unfair and at the expense of other athletes, with the biological advantages used to justify exclusion from events that fit with their gender identity, even if they have transitioned. Scientific research suggests that there may be an advantage for trans women in women's events, though this is far from definitive and does not mean that trans athletes should not compete. There is no evidence that trans athletes dominate their sport. Despite almost two decades of eligibility, the first openly trans athletes qualified for the Olympics. One of the athletes scored a medal. Hubbard and Smith were both competitors. Media coverage was dominated by Hubbard.
The activists spoke out against the bans because they were not based in science. The interim president of the Human Rights Campaign said that the FINA decision was a blatant attack on trans athletes who have worked to comply with longstanding policies that have allowed them to participate for years. Madison said the policy was an example of swimming organizations "caving to the onslaught of ill-informed, prejudiced attacks" against one particular swimmer. The organization said that the policies are driven by discrimination.
The World Swimming Federation doesn't allow most trans women from elite events or open competition.
There will be record numbers of openly gay athletes competing in Beijing.
This is the first openly trans and nonbinary Olympics.
There is a battle over gender therapy.