The Court of Arbitration for Sport began a public hearing Monday to allow cyclist André Cardoso challenge a four-year ban for doping.

Cardoso’s lawyers took the option to request a rare hearing in open court for registered media and observers to attend.

Chinese swimmer Sun Yang was the first party to a CAS case that requested an open-door process since the court modified its rules to allow more scrutiny suggested by a European Court of Human Rights ruling in 2018. Sun’s hearing was held in November and a verdict is expected this month.

Cardoso is appealing against a ban imposed by the International Cycling Union after his positive test for the hormone EPO two weeks before the 2017 Tour de France. The Portuguese racer was due to ride in support of Trek-Segafredo team leader Alberto Contador.

Cardoso was connected to the hearing by a video link.

The case has been complicated by the backup sample provided by Cardoso not matching the original sample that tested positive for the endurance-boosting hormone.

His lawyer, Yasin Patel, argued the burden of proof had shifted unfairly on his client.

“He is effectively having to disprove something that they (the UCI) can't prove,” Patel told the panel of three judges. “Uncertainty has to benefit the athlete and not the governing body."

The world cycling body's lead lawyer, Antonio Rigozzi, argued the initial sample was reliably tested for EPO, and the required “satisfactory explanation” for the difference was likely degradation in the backup sample.

“It is not a matter of fault, it is a reality," Rigozzi told the panel of arbitrators.

The initial positive test for EPO was “crystal clear,” said an expert witness for the UCI, Guenter Gmeiner, director of the World Anti-Doping Agency-accredited laboratory in Seibersdorf, Austria.

A verdict is not expected for several weeks.

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