In July 1950, the first mandatory sex verification tests in sports are issued by the International Association of Athletics Federations (IAAF) for women athletes.
This comes about because of a suspicion that men are competing in women's events "in disguise." As such, only women athletes are tested.
Gender testing will be mandatory for all "female" athletes until the year 1992, and is only used now on the premise of suspicion if an athlete shows a physical advantage.