The Cologne lab handled Alberto Contador's urine samples from the 2010 Tour de France that tested positive for clenbuterol, which he claims came from eating Spanish beef. Contador was cleared by the Spanish cycling federation this month, and the International Cycling Union and WADA are weighing an appeal to CAS.

In documents submitted to CAS, Tong's lawyers also cited the case of German table tennis player Dimitrij Ovtcharov, who was exonerated after he, and four teammates, tested positive for clenbuterol from eating contaminated meat.

The judo federation said it would have argued that the drug would have left Tong's body in the week between leaving China and being tested in the Netherlands.

The federation's lawyers told CAS that clenbuterol is banned in the European Union so "the risk of finding clenbuterol-contaminated meat in Rotterdam is therefore very slim if not non-existent."

Tong's ban denied her the chance to seek a third straight title at the Asian Games in Guangzhou, China, last November.

The 28-year-old judoka's victory in Rotterdam was her fourth straight world title. She also won heavyweight gold at the 2008 Beijing Olympics.

The CAS decision makes Tong eligible to defend her title at next year's London Olympics. Under IOC rules, any athlete receiving a doping ban of six months or more is automatically banned from the next Olympics.

The judo federation's failure to observe rules meant the panel never considered both side's detailed arguments.

Tong employed lawyers who won back Olympic medals for two Belarussian hammer throwers by arguing that their samples which contained testosterone were mishandled by the laboratory.

Tong submitted a lie detector test in support of her claim of innocence, and her legal team prepared to argue that a lab machine was not calibrated properly to detect clenbuterol.