The Origins of Cannabis Prohibition in California is the little-known story about how California became one of the first US states to ban cannabis at the turn of the 20th century and the first to relegalize its medical use and ignite an industry for all adult use at the turn of the 21st. California's 1913 cannabis ban was not caused by “Reefer Madness,” anti-Mexican prejudice, or any publicly perceived problem, but by a preemptive bureaucratic initiative.

California’s pioneering Prohibition law was sponsored by the state Board of Pharmacy as part of a wider, aggressive anti-narcotics campaign originally aimed at opiates, despite no broader public concern about cannabis at the time. The law was originally proposed by board member Henry Finger, supposedly to prevent the spread of cannabis use by “Hindoo” immigrants.

Prior to 1913, evidence for the use of “hashish” in California was exceedingly slim, and Mexican “marihuana” was not familiar to the public until after the law was passed. The board began staging raids against marihuana in the Mexican district of Los Angeles in 1914 as part of its campaign.

Despite increasing penalties, use gradually spread during the 1920s and after. .