Three-time Olympic champion swimmer Sun Yang has been given an eight-year ban for breaching anti-doping regulations.
The sanction was handed down on Friday after the Court of Arbitration for Sport (CAS) upheld the World Anti-Doping Agency's (WADA) appeal against the decision from FINA, the international swimming federation, to clear Sun of wrongdoing over allegations stemming from a visit to his home by out-of-competition testers in September 2018.
CAS determined the 28-year-old violated rules relating to "tampering with any part of doping control" and imposed the maximum sentence requested by WADA.
The fact Sun served a three-month ban in 2014 for testing positive for prohibited stimulant Trimetazidine factored into the court's decision to issue him with an eight-year period of ineligibility.
A statement issued by CAS read: "Following a conflictual anti-doping test at the residence of Sun Yang in September 2018 which resulted in the testing not being completed, the matter was initially referred to the FINA doping panel (FINA DP) which found that the International Standard for Testing and Investigations (ISTI), the protocol adopted by the World Anti-Doping Agency (WADA) for the conduct of doping controls, had not been properly followed.
"Therefore, the FINA DP invalidated the sample collection. As a consequence, the FINA DP determined that the athlete had not committed an anti-doping rule violation.
"WADA filed an appeal at CAS against that decision, asserting that Sun Yang had voluntarily refused to submit to sample collection and requesting that a period of ineligibility between a minimum two years and maximum eight years be imposed on him.
"The CAS Panel unanimously determined, to its comfortable satisfaction, that the athlete violated Article 2.5 FINA DC (tampering with any part of doping control). In particular, the panel found that the personnel in charge of the doping control complied with all applicable requirements as set out in the ISTI.
"More specifically, 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.
"As the 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."
WADA said in a statement responding to the decision it was "satisfied that justice in this case has been rendered".
Olivier Niggli, the director general of WADA, added: "WADA decided to appeal the original FINA ruling having carefully reviewed it and having concluded that there were a number of points that seemed to be incorrect under the code.
"[The] CAS ruling confirms those concerns and is a significant result. We will now need to take time to review the decision in full, and we will continue to review diligently all anti-doping decisions taken by code signatories to ensure they are in line with the code and, when warranted, to exercise our independent right of appeal."
Sun won gold in the 400-metre and 1500m freestyle at London 2012, before topping the podium over 200m in Rio four years later. He has also claimed 11 World Championship titles, two of which came in Gwangju last year.
CAS confirmed the ban would take effect from Friday, with his results since September 2018 standing because he was not provisionally suspended by FINA. He tested negative for prohibited substances shortly before and after the incident at his home, and there was no evidence he may have engaged in doping activity since.