An alternative: Hemp?

Last class session, Professor Webber asked the following question:
“What percentage of gasoline used in the U.S. would be replaced by ethanol, using current corn-based production technology, if every acre of corn was used for ethanol production exclusively”
And the answer was “B. 11-25%” which we know is not sufficient in meeting the demands of the American public. But why turn to corn when there exist an alternative crop that is “estimated [to have] 25,000 plus uses, for producing food, fuel, medicine, paper, plastics, and even dynamite” (Bower, 46, 2003). This alternative crop can grow in approximately any habitat and it does not cut into the demand for food. This crop is Cannabis sativa L ( Grotenhermen, xxix, 2002), or better know was hemp.
But the cultivation of hemp in the U.S. is currently banned. So my question is as follows: Why the ban on a plant that could potentially provide relief to the U.S. dependence on foreign oil?
An answer that might be given is that hemp is considered to be marijuana, but in actually hemp and marijuana can be consider to different breeds. There are two main chemical components present in hemp and marijuana, THC is the “psychoactive ingredient” and CBD is the “anti-psychoactive ingredient” (Grotenhermen, 63, 2002). CBD is the main component in hemp; thus blocking any “high” effect that one might experience when smoking marijuana. Another concern is the possibility of individuals growing marijuana instead of hemp. This dilemma can be contained because there is a distant difference between the plants.
And it’s not like the U.S. hasn’t taking advantage of the many uses of hemp. Hemp provided many usages during the colony time and even after the Marijuana Tax Act of 1938, the U.S. government endorsed the growth of hemp for WWII with the “Hemp for Victory” campaign. The video can be view at http://www.youtube.com/watch?v=Ne9UF-pFhJY. There’s also a video that demonstrates a car made from hemp fibers at http://www.youtube.com/watch?v=bxlj6fgQ-ZU&feature=related.
There are plenty of more examples and reasons for the cultivation and production of hemp in the U.S., but that’s what my paper is going to be about. In my opinion if there’s that much potentially in a particular commodity then why ban it?
References
Bower, J. (2003, May). Seed of hope. Ecologist, 33(4), 46. Retrieved February 14, 2008, from Academic Search Complete (EBSCO) database: http://web.ebscohost.com//?vid=1&hid=4&sid=dd9b29b3-fd28-4e40-9206-43677ba901c1%40sessionmgr2

Grotenhermen, F., MD, & Russo, E., MD (Eds.). (2002). Cannabis and cannabinoids. Binghamton, NY: Haworth Integrative Healling Press.