One of the accusations is use of a corticosteroid, the same corticosteroid he was prescribed, and that was approved for use, to treat saddle-sores.
The same corticosteroid that was approved for use (not only by Lance Armstrong) by the UCI and cleared by WADA.
Essentially, these are the same allegations that the US Government and the FBI Investigator Jeff Novitsky have been investigating for two years, and quietly dropped in January this year as nothing could be proved (much of the evidence presented to Novitsky's Grand Jury came from Floyd Landis, who is of course a rider convicted of doping, and who - publicly - has something of an axe to grind with Armstrong).
There was also the issue that in the US, there was antagonism towards the US Postal Team (as was) due to their selling-off (at a profit) of ex-Team bikes at the end of a season; Bikes which had been paid for (due to US Postal sponsorship) by the US Government.
There is surely more to this story than meets the eye!