The three biathletes were suspended for life in 2017 for doping offences at the 2014 Winter Olympic Games in Sochi, where they earned the silver medal in the 4x6 kilometres relay.

CAS suspended its review last year after agreement from all parties, with the expectation that it would proceed once decisions had been made on other remaining doping cases involving Russian athletes at Sochi 2014. 

A common hearing with the athletes took place on March 2 and 3. 

A panel of arbitrators, led by Luxembourg's Jacques Radoux, concluded that none of the acts alleged to have committed by Vilukhina and Romanova had been established to "comfortable satisfaction" and beyond the suspicion of a doping violation following testimony provided in the McLaren Report by Grigory Rodchenkov, the former head of the World Anti-Doping Agency (WADA) laboratory turned whistleblower.  

Accordingly, the panel, which also included Britain's Philippe Sands and Greece's Petros C. Mavroidis, has ordered the findings and sanctions imposed upon Vilukhina and Romanova be removed and their results in individual events at Sochi 2014 reinstated.

Vilukhina will subsequently have the silver medal she earned in the women’s 7.5 km sprint returned to her. 

It means that Ukraine's Vita Semerenko will remain in the bronze medal position and Italy's Karin Oberhofer will not be promoted to third place. 

But the panel ruled that Zaitseva committed a doping violation, with the IOC decision confirmed.  

Her life ban was still overturned, however.

Rodchenkov's lawyer Jim Walden responded to the CAS ruling with a strong statement, claiming it proved the "international system is rigged against clean athletes".

"Although it is heartening that CAS upheld the finding of doping against Zaitseva and the disqualification of the results of the Russian biathlon relay team, CAS’s acquittal of the other athletes on such a flimsy basis, despite resounding evidence of sample tampering, shows only that the international system is rigged against clean athletes," he said. 

"This proves, once again, that robust criminal enforcement of anti-doping rules by US authorities is the last, best hope for clean athletes everywhere."

Following the ruling, the defence team revealed they would appeal the decision regarding Zaitseva at the Swiss Federal Tribunal.

"We believe all three of the biathletes are innocent of doping, period," said defence team member Yvan Henzer.

"Regarding the case of Olga Zaytseva we will continue the fight to clear her name.

"The next logical step is via the Swiss Tribunal and preparations to file a case there are to begin immediately."

Russian Olympic Committee President Stanislav Pozdnyakov also responded to the ruling. 

"I am very happy for Olga Vilukhina and Yana Romanova," he said, as reported by Russian state news agency TASS. 

"It's a pity that Olga Zaitseva's appeal was rejected. 

"Now we need to look at the reasoning part of the CAS decision in order to understand why such decisions were made."

All other decisions made by the IOC were retained, including the disqualification of the results achieved by the Russian team in the women’s 4x6km event and the mixed 4x6km relay at Sochi 2014. 

When contacted by insidethegames for comment, the IOC said it "takes note of the CAS decision which we have to respect".

The trio of biathletes appealed to the CAS following sanctions by the IOC Disciplinary Commission, after their alleged involvement in Russia's state-sponsored doping scheme.

It followed evidence from the McLaren Report, as well as subsequent investigations by IOC Commissions.

The IOC’s Oswald Commission decision on Zaitseva was also one of the stronger verdicts delivered.

It claimed the Olympic gold medallist at Turin 2006 and Vancouver 2010 was a knowing participant in the state-sponsored doping scheme. 

The Commission's full reasoned decision also ruled that samples given by Zaitseva, Romanova and Vilukhina had marks indicative of tampering and were found to contain abnormal levels of salt. 

But in February 2018, the CAS overturned 28 cases involving Russian athletes, stating "the evidence collected was found to be insufficient to establish that an anti-doping rule violation was committed by the athletes concerned".

A further 11 cases were found to have enough evidence to uphold the sanctions. 

Zaitseva, Romanova and Vilukhina - who had already retired - were the only athletes whose cases were held over.

Separately, Zaitseva, Romanova and Vilukhina filed a lawsuit against Rodchenkov.

The lawsuit was backed by Russian oligarch Mikhail Prokhorov, former owner of the National Basketball Association team the Brooklyn Nets.

It claimed Rodchenkov defamed the three biathletes.

In a comment to insidethegames, WADA said it "notes the decisions published by the Court of Arbitration for Sport in these cases and will assess the full written judgements when they become available. 

"WADA cannot comment further at this time."