The Marihuana Tax Act of 1937, Pub.L. 75–238, 50 Stat. 551 (Aug. 2, 1937), imposed a tax on the sale of cannabis. It was in response to series of Hollywood movies warning against the dangers of cannabis, including Reefer Madness.
From the Archives of General Psychiatry:
| “ | The anti-marihuana law of 1937 was largely the federal government's response to political pressure from enforcement agencies and other alarmed groups who feared the use and spread of marihuana by "Mexicans." ... [T]he Federal Bureau of Narcotics resisted the enforcement burden of the antimarihuana law until mounting pressure on the Treasury Department led to a departmental decision, probably in 1935, to appease this fear, mostly in the Southwest and West, by federal legislation.[1] | ” |