The anti-doping regime in sport is demanding. Athletes must cooperate with random testing during and outside competition. There are few if any excuses for banned substances in the blood or urine or for refusing or aborting tests. The consequences are punitive suspensions from competition that can be career-ending and financially devastating. The reputational taint is lasting. In the case of China’s swimming superstar and Olympic champion Sun Yang, an eight-year ban by the Court of Arbitration for Sport over refusal to cooperate with a test would have sidelined him until age 36. What amounts to a ban for competitive life may seem excessive. But any less rigorous an anti-cheating regime is unlikely to sustain the integrity of professional sport and Olympic competition. That being the case, however, the testing and enforcement processes must be beyond reproach. There can be no room for doubt, for example, about the accreditation of members of the testing team. This is said to be the issue that led to Sun’s entourage destroying blood samples and Sun refusing to take further tests at his home in Hangzhou in 2018. Nor is there room for perceptions of anti-China bias on the part of the chairman of the court, arising from tweets critical of alleged animal cruelty by some on the mainland, and containing racially charged language. What does the latest ruling mean for Sun Yang’s Olympic hopes? The court ruled that Sun had failed to establish a compelling justification for his actions, and also took into account a previous three-month suspension for taking a banned in-competition stimulant for what he said was a heart condition. A Swiss federal tribunal has now overturned the disqualification and ordered a rehearing before the court. Sun is China’s most highly recognised sports superstar since basketball player Yao Ming and women’s grand slam tennis champion Li Na. Reaction in China to his banning is mixed, from sympathy to disapproval of the way he handled his situation. Some see him as uncooperative with drug testing. Given the nationalistic overtones in sport, a sense of fair play may be tested on occasion. It is important that justice is seen to be served while the integrity of sport is safeguarded. The rehearing is the least that could have been done in both respects.