See above. First of all, there was Ben Johnson. Then came Lyle Alzado. Last but certainly not least, in light of recent events came Senator Joe Biden. Biden was "convinced" (you could say "bought" and not be as wrong as you should be) by the professional sports lobby in Washington that it would be good for "the integrity of the game" if these pharmaceuticals became controlled substances. So Joe started hearings. He called out the big guns; the AMA, the DEA, the NIH, the whole gamut. The problem was that ALL OF THOSE WITNESSES TESTIFIED THAT STEROIDS, WHATEVER MAY BE OTHERWISE WRONG WITH THEM DID NOT MEET THE STANDARD FOR SCHEDULING! Undaunted, he called other witnesses, relied on purely anecdotal evidence, called for "controlling this new drug problem", and voila! More drug laws. Contrary to the testimony of expert witnesses who said that while there may be some reason to place some additional restrictions on the availability of steroids, adding then to the Schedule of Controlled Substances was not warranted. The spirit of Prohibition lives!
You should really check out the links in my original tirade. They answer your very good question and more!