After decades of intransigence on the issue, the Drug Enforcement Administration may finally recommend removing marijuana from the list of the country’s most dangerous drugs. That list was created as part of the Controlled Substances Act (CSA) of 1970, which consolidated all federal drug laws into a single comprehensive measure and defined marijuana as a Schedule I controlled substance, alongside heroin, LSD and other drugs that the government says have no medical value and the highest potential for abuse. That meant marijuana was saddled with the strictest possible restrictions and penalties.

Ever since then, marijuana activists have been fighting to remove cannabis from that category. In 1972, the National Organization for the Reform of Marijuana Laws (NORML) petitioned the DEA to instead place marijuana in Schedule II of the CSA, alongside cocaine, meth and other drugs considered dangerous but with medical potential. Twenty-two years and multiple courtroom battles later, the DEA had a final decision:...