THE NEW YORK TIMES ran an investigative series of articles in the late 1980s about the steroid trade, its history & development. According to those reporters, several things happened in the 1980s that got the attention of the feds. At that point, it was a hundred million dollar annual illegal industry in the US (it's more than that in 2006, of course). The first thing that got the feds' attention is that high school athletes were dropping dead from self-injecting veterinarian steroids they were buying on the street. The parents of these boys were screaming bloody murder that the feds had to do something, & do it fast. Also, the Mafia got involved in distribution. It had become more profitable to distribute steroids than heroin. Wise guys were walking into gyms & telling gym owners they would be killed if they didn't start fronting steroids to their members. Meanwhile, the IOC (International Olympic Committee) was screaming bloody murder about the juiced athletes in their competitions (& juiced all sorts of ways, not just AAC).
In 1990, the feds did the easiest thing they could do address the problem: they passed the Anabolic Steroid Control Act, classifying unprescribed anabolics as the equivalent of narcotics, in effect making them "controlled substances." That prevented MDs from being able to prescribe them to athletes for "recreational use" (i.e., no medical need). Meanwhile, this prohibition led (as Prohibition of alcohol did in the 1920s) to an explosion of use, as underground labs started cranking all sorts of designer 'roids out for the masses. The legal use of prohormones due to the dietary supplement law in 1994 created a gap that recent laws have closed up. Also meanwhile, more laws have gone into effect further criminalizing steroid use & possession, including a recent "emergency" law that makes any illegal use of anabolics a serious federal crime. Now anyone who looks like a bodybuilder who goes through US Customs is treated like a potential criminal.
The upshot is this: being a bodybuilder is close to being a federal crime in the US.
http://www.mesomorphosis.com/articles/collins/wrong-prescription.htm