just repeal the tax act of 1937 and that would end the debate...
http://www.druglibrary.org/schaffer/hemp/taxact/mjtaxact.htm
The Marijuana Tax Act was found unconstitutional by the USSC back in the 70's, and replaced by the Controlled Substances Act during the Nixon Administration. He also gave us the EPA, authorized under the same claim of authority - the New Deal "substantial effects" interpretation of the Commerce Clause.