The scientific evidence is very clear. Male chromosomes give performance advantages in sports that rely on strength, power or endurance. At the Olympic Games, even the smallest margins can be the difference between victory and defeat. So it’s absolutely clear that it would not be fair for biological males to compete in the female category. In addition, in some sports, it would simply not be safe. Every athlete must be treated with dignity and respect, and athletes will only need to be screened once in their lifetime. The I.O.C. recognizes the importance of widespread participation in grassroots and recreational sports programs, and the impact that sport has in society. However, the Olympic Games has a focus on elite sport, and in elite sport we must ensure the fairness, safety and integrity of all competitions within the Games.