I wish there was a way to test or prove Obama is actively using drugs. Get a urine or hair sample?
How about this question for the next town hall meeting:
Mr. President, in your books you admit that as a youth you were “an enthusiastic” drug user and abused both marijuana and cocaine. We know that drug use can become addictive for life. What treatment program or method did you use to stop taking drugs and have you used illegal drugs during you time in office as president?
You probably won't have much luck procuring one yourself but I would guess the KGB has any number of them on hand and analyzed in their Gas Chromatography lab.