Sun will miss the Tokyo 2020 Olympics after a four year and three month ban, effective from February 28 2020, was imposed, although under the ruling he would be eligible for Paris 2024.

The CAS appointed an entirely new panel to hear the case after the World Anti-Doping Agency (WADA) appealed a decision by the International Swimming Federation (FINA) in 2018 not to ban the swimmer for the violation.

The CAS handed Sun an eight-year ban in February 2020, a verdict the 29-year-old successfully appealed to the Swiss Federal Tribunal.

The Swiss Federal Tribunal ruled the case needed to be reheard as the President of the previous panel Franco Frattini was removed over a series of discriminatory tweets.

Following a three-day virtual hearing the new CAS panel found Yang committed two Anti-Doping Rule Violations (ADRVs) in breach of two articles of the FINA Doping Code.

The panel found Yang guilty of evading, refusing or failing to submit to sample collection by an athlete and tampering or alleged tampering with any part of doping control by an athlete or other person.

In its verdict, the new panel found Sun to have acted recklessly when he refused to allow Sample Collection Personnel to leave with his blood samples after an out-of-competition anti-doping control test at his home in September 2018.

A member of the swimmer’s entourage allegedly smashed a blood vial with a hammer during the incident, with Sun claiming the testers were not properly qualified.

Sun previously served a three-month drugs ban in 2014 after testing positive for trimetazidine, a banned stimulant, with the new CAS panel ruling the September 2018 incident to be a second ADRV.

The new CAS panel said it concluded this incident to warrant a period of ineligibility at the lower end of the range and imposed a ban of four years and three months, effective from February 28 2020.

The new panel consisted of Dr Hans Nater of Switzerland as President, Professor Jan Paulson of France and Professor Bernard Hanotiau of Belgium.

In a statement following the release of the outcome of the case FINA said: "FINA acknowledges the decision rendered by the Court of Arbitration for Sport in the case WADA v. Sun Yang and FINA.

"FINA confirms that Mr Sun Yang (CHN) has been sanctioned for 4 years and 3 months, effective as from February 28, 2020. 

"FINA will enforce the CAS Award according to its terms, and in accordance with its obligations as a signatory to the World Anti-Doping Code.

"FINA remains committed to the protection of all clean aquatics athletes worldwide and will carefully consider the 90-page award."

In a statement WADA said it welcomed the ruling, with the organisation's director general Olivier Niggli saying: "The decision by the Swiss Federal Tribunal to set aside the CAS award was limited to a challenge made against the Chair of the CAS Panel and had nothing to do with the substance of this case. 

"Today’s ruling reconfirms WADA’s position in relation to the original FINA ruling, which was that there were a number of points that were inconsistent with the Code. Today’s CAS ruling validates those concerns."