The global anti-doping system is "failing athletes", American figure skater Vincent Zhou said on Monday ahead of Russian Kamila Valieva's doping case, which will be heard by the Court of Arbitration for Sport (CAS) from Tuesday to Friday.

Russian Valieva tested positive for the banned substance trimetazidine at the Russian national championships in December 2021 but the result was only made known on Feb. 8, 2022 a day after she helped her team win gold at the Beijing Olympics.

The International Skating Union (ISU) had lodged an appeal to CAS, sport's highest court, after a Russian investigation found the teenager not guilty of a doping infraction despite acknowledging she failed a drug test.

The U.S. team of Zhou, Evan Bates, Karen Chen, Nathan Chen, Madison Chock, Zachary Donohue, Brandon Frazier, Madison Hubbell and Alexa Knierim took silver behind the Russians in Beijing, with Japan getting the bronze and Canada placing fourth.

However, during the Beijing Games, the International Olympic Committee (IOC) decided no medals for the team figure skating event would be presented until Valieva's case had been resolved.

"As my team's empty medal boxes show, the global anti-doping system is failing athletes. The revered elitism of the Olympics is dependent upon the principles of clean sport and fair competition," Zhou said in a statement.

"Whenever finally held, the awards ceremony for the Beijing 2022 Figure Skating Team Event will be a symbol of the gross failures of the IOC, CAS, RUSADA (Russian Anti-Doping Agency), and other global sporting administrators.

"Justice delayed is justice denied, and my team mates and I will never get back the chance to stand before the world to celebrate a lifetime's worth of hard work culminating in a career-defining achievement."

Reuters has contacted the IOC, CAS and RUSADA for comment.

While Valieva's hearing involving RUSADA, the ISU and the World Anti-Doping Agency (WADA) begins on Tuesday, CAS have said they cannot be sure when the final decision will be announced.

Zhou added that the U.S. team had asked to observe the hearing, but were told that it was confidential.

"We were told that either of the involved parties could request a public hearing, but that neither did. For that reason, the proceedings will happen behind closed doors," Zhou said.

"An open and transparent hearing would go a long way towards helping athletes understand any decision that is rendered."

(Reporting by Aadi Nair in Bengaluru; Editing by Ken Ferris)