Russian figure skater Kamila Valieva has been given a four-year ban for dipping after initially being cleared.
A Russian Anti-Doping Agency (Rusada) investigation found the teenager bore "no fault or negligence" for a failed test before the 2022 Winter Olympics, where she won team gold at age 15.
The Court of Arbitration for Sport (Cas) has upheld an appeal by the World Anti-Doping Agency (Wada).
"The doping of children is unforgivable," Wada said in response.
News of Valieva's failed test only emerged after she had helped Russia win gold in Beijing.
The ban has been backdated to December 25, 2021 - the date Valieva took the failed test - and the Cas panel has also ordered "the disqualification all competitive results achieved" from that date.
However, it said the power to strip Russia of the gold medal was "not within the scope of this arbitration procedure and will have to be examined by the sports organisations concerned".
The governing body, the International Skating Union welcomed the Cas decision and said it will publish a full statement with regards to the implications on Tuesday.
Cas said Valieva, who is now aged 17, did not contest the presence of a banned substance and it was asked to decide what sanctions, if any, she should face.
"Ms Valieva was not able to establish, on the balance of probabilities and based on the evidence before the panel, that she had not committed the Anti-Doping Rule Violation (ADRV) intentionally," it said in its ruling.
It added it had no bearing on "whether the athlete is an adult or a Protected Person" referring to Valieva's age at the time of the failed test.
The Kremlin has criticised the Cas ruling as a "politicised" decision, while the Russian Olympic Committee said: "In effect, war has been declared on Russian sport."
