Good find. Bored at work, so did some half-assed research. It looks like there are some serious organizations that are against the use of any type of performance enhancers, regardless of prescription status. WADA is the World Anti-Doping Agency, and they publish a list of officially banned(or opposed? it's unclear who really plays by these rules) substances every year. The 2010 list is split up into a few parts. The 'prohibited in or out of competition' list includes steroids and all that other shit Mark McGuire took. The 'prohibited in competition only' list includes all stimulants, narcotics, and, of course, cannabinoids.
- http://www.wada-ama.org/Documents/World_Anti-Doping_Program/WADP-Prohibited-list/WADA_Prohibited_List_2010_EN.pdf
the trouble with cannabinoids is how slowly your body metabolizes them. those other substances stay in your system for a few days; a chronic pot smoker will have dirty piss for a month. so, as per the MAP/IOC/WADA, you could just stop taking your ADHD meds 72 hours before competing, and you'll be fine, but if you smoked a joint a few weeks before, you'd be fucked come competition time.
I think that's the argument for random drug testing before: you shouldn't be able to use performance medications for any length of time before competition. A kid that's constantly on speed might train way way harder for weeks and then just go off them a few days before competition and still reap the benefits. But at what cost to the athletes do we level the playing field? Do you take a kid off prescriptions for maybe months so that he doesn't get any more performance enhancement than a kid without ADHD? That would be more than we do with academics, but we strangely seem to take academics as a competition much less seriously than sports.
And if anyone is still wondering if THC is performance enhancing in a subjective/style-based comp, you ever hear of Candide Thovex? Nobody in their right mind would grab blunt so long if they were sober. Or do sw cork 7s onto rails.