The tactic has been increasingly favored by the IRS since 2008, when the U.S. tax agency began conducting audits of major California dispensaries. One of the first businesses targeted by the IRS was the Martin Alliance for Medical Marijuana, which was forced to shut its doors after the IRS cited § 280E of the federal tax code, which prohibits deductions on sales of controlled substances, and demanded millions of dollars in back taxes.
“Every dispensary in the nation, past, present and future is dead if this is upheld,” the Lynette Shaw, owner of the Martin Alliance dispensary, told The Martin Independent Journal.
http://www.rawstory.com/rs/2012/08/06/tax-court-burns-entire-u-s-medical-marijuana-industry/