Whenever a pro cyclist gets caught with an illegal substance in his blood or urine, he or she inevitably appeals the charge and/or sentence. Fighting it is pretty much the only way a rider can maintain innocence or feign integrity -- if you don't appeal, you may as well brand "doper" on your forehead. The only other strategy I've seen is virginal contrition: "I'm so sorry I did it, this was the first and only time I ever used drugs, why was I so stupid?" Of course, the cynics among us translate that as "I'm so sorry I got caught, this was the first and only time I ever got caught using drugs, why was I so stupid to get caught?"
Sometimes appeals are successful. Anomalies are found in testing procedures, false positives are identified, lapses in protocol occur, etc. As for sentencing, sometimes a cyclist can get his suspension reduced or at least changed to start the day after he stopped racing rather than the day he was found guilty. This was the case with David Millar, who may race the Tour de France this year thanks to his sentence being applied retroactively (he also tried to get his sentence reduced but failed).
Anyway, the appeal strategy backfired terribly this week for Danilo Hondo. He was hoping for an acquittal because although he tested positive for the stimulant Carphedon, there supposedly wasn't enough present to provide any performance gain. Alas, the Court of Arbitration for Sport instead determined that Hondo had been under-sentenced with a one-year suspension when he should have been suspended for two years. In addition to the two-year suspension, Hondo cannot race in the Pro Tour (the top level of pro cycling) for another two years. Oops. Hondo had hoped to return to his Gerolsteiner team in April, but now he may not be back at all.