Countries Have Long Tested Their Own Athletes for Doping. That Could Soon Change.

After Chinese swimmers won Olympic gold in 2021 despite having tested positive for a banned substance, the World Antidoping Agency is considering whether to have an independent body handle testing before major events.Zhang Yufei, center, at the meet where she tested positive for a banned substance in January 2021. Months later, she won four medals, including two golds, at the Tokyo Olympics.