Olympic Doping Scandals: Past and Present

Of the 10,500 athletes competing in the 2012 London Olympics, nearly half of them, including each medal winner, will be tested for 240 banned substances. American judo fighter Nicholas Delpopolo, 23, was expelled from the Olympics on Aug. 6 for failing a drug test, which he said was caused by mistakenly eating something that had been baked with pot. (Paul Sancya/AP Photo)