China’s three-time Olympic champion Sun Yang has been banned from competing for eight years for missing a doping test in September 2018.
The 28-year-old was initially cleared of wrongdoing by Fina, the swimming federation, in January 2019.
Following an appeal by the World Anti-Doping Agency (Wada) to the Court of Arbitration for Sport (Cas), the decision has been overturned.
An eight-year ban was imposed on Sun because this was his second offence.
The freestyle specialist had served a three-month suspension in 2014 for taking prohibited stimulant Trimetazidine.
He won 200m freestyle gold at Rio 2016 having triumphed in the 400m freestyle and 1500m freestyle at London 2012.
Sun had told an appeal hearing in November that he missed a test because testers failed to prove their identity when they arrived at his home.
He also denied a vial containing his blood samples was smashed with a hammer.
Cas said: “The athlete failed to establish that he had a compelling justification to destroy his sample collection containers and forego the doping control when, in his opinion, the collection protocol was not in compliance with the ISTI (International Standard for Testing and Investigations).
“As the Cas panel noted, it is one thing, having provided a blood sample, to question the accreditation of the testing personnel while keeping the intact samples in the possession of the testing authorities; it is quite another thing, after lengthy exchanges and warnings as to the consequences, to act in such a way that results in destroying the sample containers, thereby eliminating any chance of testing the sample at a later stage.”
At the World Aquatics Championships in July 2019, Sun won gold in the 200m freestyle but Britain’s Duncan Scott refused to share the podium with him.
Australian swimmer Mack Horton took a similar stance after the 400m freestyle, years after accusing him of being a “drug cheat”.