28 Russian athletes have had their bans on competing in Olympic events overturned and their results reinstated.
The athletes were banned for life after investigations found they had been involved in state-backed doping at the Sochi games in Russia in 2014.
The Court of Arbitration for Sport (CAS) ruled there was "insufficient" evidence that the 28 - including several medallists - had broken anti-doping rules.
Matthieu Reeb, Secretary-General of CAS, said: "This does not mean that these 28 athletes are declared innocent, but in their case, due to insufficient evidence, the appeals are upheld, the sanctions annulled and their individual results achieved in Sochi are reinstated."
Those who have had their bans overturned may be able to gain late entry into the upcoming Winter Olympics in the South Korean city of Pyeongchang, which start on 9 February.
A lawyer has said that they will be seeking to do so.
The International Olympic Committee (IOC) has banned Russia from the Pyeongchang games, but has invited 169 Russians who had no involvement in doping to take part under a neutral flag.
A 17-month probe by the World Anti-Doping Agency (WADA) found "beyond reasonable doubt" the Russian Ministry of Sport and its Olympic preparation team had allowed state-funded doping at Sochi.
The IOC may now be forced to allow in athletes it deems dopers, eight days before the next games begin.
Bans
A total of 43 Russians were originally banned over doping offences at the Sochi Olympics.
CAS also partially upheld appeals for 11 of them, but only lifted their lifetime bans, and continued to prevent them from taking part in Pyeongchang.
The Russian government vehemently denies ever supporting doping.
The bans on three members of the Russia's second unit in the men's four-man bob are among the 11 whose bans have been partially upheld, which means the UK's upgrade to bronze is confirmed.
But among those now cleared of cheating at Sochi 2014 are men's Olympic skeleton champion Aleksander Tretiakov, the current women's European and World Cup skeleton champion Elena Nikitina and Olympic cross-country gold medalist Alexander Legkov.
The IOC has also banned numerous Russian politicians and officials from the Pyeongchang games over the doping scandal, including deputy prime minister and former sports minister Vitaly Mutko.
Kremlin spokesman Dmitry Peskov said Moscow will continue taking legal measures to defend its athletes banned from the Olympics by the International Olympic Committee (IOC).
"We are very glad for our athletes," he added.
Among those who took part in the appeal hearings were the former head of the Moscow anti-doping laboratory Dr Grigory Rodchenkov, who fled to the United States in 2015 and has become the main whistleblower in the Russian doping scandal, and Professor Richard McLaren, the legal expert who examined Rodchenkov's claims on behalf of WADA.
