At a time where trust in sport is at an all-time low, a group of hackers calling themselves Fancy Bears last week spun sporting credibility into chaos by revealing the names of athletes who have been taking banned drugs under the TUE system. TUEs, or therapeutic use exemptions, are permissions for athletes to use banned drugs for medical conditions.The athletes who have been "outed" are not doping, but, in the absence of confidence in the system, fans are confused about what constitutes doping.Fancy Bears revealed that, on multiple occasions, Serena Williams had been prescribed a powerful drug, a corticosteroid, used for asthma, allergies and skin problems .Brad Wiggins and Chris Froome, Britain's two Tour de France champions, had TUEs for corticosteroids, Wiggins for asthma and Froome for chest infections.Wiggins is a striking case because he's an asthmatic. He was given a powerful steroid injection within a week of big multi-stage cycling races on three occasions. This was after he had denied ever receiving an injection. His team, Sky, denied ever using the TUE system for allergies, two years after he'd done it three times.Publishing a list of athletes with TUEs is not a smoking gun, but it does question attitudes to doping .There are only three options around TUEs. First, there are genuine cases . The athlete suffers from a chronic condition and a doctor prescribes treatment using a banned drug. The application goes through, the athlete is back to normal (but not better, in theory - this is key), and the system is working.Unfortunately, Options 2 and 3 ruin this panacea. In Option 3, the athlete fabricates a medical problem to get the drug because it has powerful performance-enhancing effects. Cyclists have been taking cortisone for decades, knowing how powerful an effect it can have on weight loss (highly desirable), chronic and acute pain, fatigue and general resistance to fatigue.We know, thanks to testimony from more than one elite athlete, that they will fake a problem - tendon injury, for instance - to get the drug, and race as a doper, but "legally". This is above board, even though it's a case of doping. The abuse of the TUE process, aided and abetted by doctors, makes it appear legitimate.Option 2 is the grey area. An athlete has a condition and is justified in seeking medication . But the athlete and a supporting doctor are "opportunistic", and ask for permission to use a drug that is a little stronger than what the athlete needs. The condition did not warrant it, but a loophole is exploited .Nobody knows how many examples of each option exist. At the heart of the controversy is that sport has earned itself an all-time low level of trust. Where it ends is anyone's guess, but it may be a starting point for a house of cards, already shaky, to fall under the sheer weight of scepticism...