How can purchase rohypnol?

You can't. From the dea's website "in addition, in 1997 the u. S. Sentencing commission increased the penalties associated with the possession, trafficking, and distribution of rohypnol to those of a schedule i substance. (schedule i substances include heroin, marijuana, and mdma.)" making it illegal to sell, buy or to posses.
Why? I agree with dr. Windich. Why would you want to purchase rohypnol, knowing that it is used as a "date rape drug"? It's use is banned in the United States.