Ross Rebagliati was the Canadian snowboarder who tested positive for marijuana after winning the Gold in 1998. His team argued successfully that the minute amount that was found in his system was due to second hand smoke from all the pot smokers at Whistler.

It was mentioned at the time that marijuana could possibly calm someone down before such an event, which was why I mentioned the beta blockers in a previous post.
Athletes often get screwed by mistakes made by so-called experts. Silken Laumenn was suffering from a dry cough before the 1995 Pan American games and was advised by her teammates to take Gravol on the train ride so she could sleep, which, although it's not banned, was bad advice. She talked to her doctor and he advised her to take Benadryl, presumably because it would help her sleep and was a wider acting antihistamine than Gravol (dramamine). Another bad piece of advice because a dry cough usually means you have thick mucus in the lungs and an antihistamine would dry it even more. The correct medicine would be an expectorant to loosen the phlegm. So, Silken went to the store to buy Benadry, and at that time, in Canada anyway, you had to ask for it over the counter. There was only one store I knew of that carried a variant of Benadryl with a decongestant - 60 mgs. of pseudoephredine ( a banned substance at the time) and they kept that on the shelf, while the plain Benadryl was behind the counter. So, she goes into a store, sees Benadryl on the shelf and buys it. She's a rower, not a pharmcist or a doctor, and shouldn't be expected to know what all the ingredients are in cold medicines. She was stripped of her medal and possibly lost money from sponsorships.
It was the same with Kyoko Ina - the USADA drug tester showed up at her house late at night when she was about to go to bed. She told them she couldn't produce a sample at that time, but would first thing in the morning. The tester, whose credentials had expired , and showed up with her boyfriend, had her sign an "Athlete Refusal Form" and they arranged for the test to be done the next morning, however the tester did not show up. You can read Ina's statement here:
http://www.figureskatersonline.com/ina-zimmerman/news_articles_003.html