More than 20 witnesses will be testifying over the next four days in Lausanne as Alberto Contador’s clenbuterol case finally gets its day before the Court of Arbitration for Sport in Lausanne, Switzerland.

At noon on Monday begins the first of three days of hearings before a three-member panel that will decide the fate of the three-time Tour de France champion, who claims traces of clenbuterol found in his system on a rest-day control late in the 2010 Tour came from consuming contaminated meat.

On Thursday, lawyers on both sides will make their final arguments. A final ruling isn’t expected until early 2012.

Among the first wave of witnesses set to appear before CAS is the Spanish butcher who allegedly sold the infamous steaks that Contador dined on during the Tour’s second rest day. Contador’s urine samples later showed 50 picograms of the anabolic agent in his system; as there is no permissible threshold for the substance, he could face a two-year ban and the loss of his 2010 Tour title.

According to Contador’s lawyers, José Luis López Cerrón, race director of the Vuelta a Castilla y León, traveled from Spain to France as the Tour entered the Pyrénées. Along the way, he stopped at a butcher in Irún, inside Spain’s Basque Country, to buy steaks before taking them into France.

Insiders say such dinners are part a long-running tradition among Spanish teams as the Tour nears Spain, when special meals are prepared with Spanish cheese, cured hams and other Iberian delicacies served up to homesick riders.

Receipts produced by Astana — Contador’s team during the 2010 Tour — showed that the butcher belonged to Grupo Larrezabal, which sold the cuts of beef that Contador’s lawyers argue triggered the clenbuterol positive.

Speaking to the Spanish daily El Diario Vasco, butcher Javier Zabaleta spoke to the media for the first time since the shop became the center of media focus.

Zabaleta, who has worked more than 30 years in the meat industry, is expected to testify today after being requested to appear before CAS by the World Anti-Doping Agency (WADA) and is expected to recount how beef sold in Spanish butchers is documented, controlled and catalogued.

“All beef has its certificate, with a registered number, the date of the slaughter, the date of birth of the animal, the date of feeding, a health number and the number of the butcher,” he told the newspaper. “All of our papers are in order.”

WADA investigators visited the butcher’s shop earlier as part of its investigation into the case, Zabaleta said.

Contador’s legal team will argue that despite clenbuterol being banned since the 1990s within Europe for use in livestock destined for human consumption, that illicit fattening of beef still occurs. Sources told VeloNews that lawyers will also press the idea that beef might have been imported from beyond the stricter controls of the European Union.

Zabaleta said that he buys his beef from a local provider, which he refused to name publicly, but said that meat likely did not come from Spain’s Basque Country.

“It’s impossible” to determine exactly where the steaks might have come from, he said. “The meat is from another region, but I cannot tell you if it’s León, Salamanca or Catalunya, but it’s not from (Basque Country).”

Despite dropping appeals in two other recent clenbuterol cases, WADA is sticking to its guns in the Contador case. According to the Spanish sports daily AS, WADA will push the argument that the clenbuterol entered Contador’s system as part of an illicit transfusion of blood.

Calling witnesses such as Zabaleta is part of their strategy to demonstrate that Spanish beef sales are highly controlled and regulated. In 2006, for example, there was only one case of clenbuterol among 2,600 samples tested by the Spanish government. Other years from 2004-2009 found no clenbuterol positives among thousands of controls.

Contador, meanwhile, is likely to testify on his own behalf later this week. The court proceedings are not open to the public or the media.