Wrong. Marijuana is a controlled substance i had that specifically clearified to me when entering the USA through US Customs. If you dont want to believe me, then click the following link.
(6) The term ''controlled substance'' means a drug or other substance, or immediate precursor, included in schedule I, II, III, IV, or V of part B of this subchapter. The term does not include distilled spirits, wine, malt beverages, or tobacco, as those terms are defined or used in subtitle E of the Internal Revenue Code of 1986.
http://en.wikipedia.org/wiki/Controlled_Substances_Act