Also, many countries (186) are nominally still party to the 1961 Single Convention on Narcotic Drugs, which puts marijuana in "Schedule IV:" "The drug … is particularly liable to abuse and to produce ill effects, and such liability is not offset by substantial therapeutic advantages." So even above-board international trade in cannabis may be problematic.

> The Commentary notes that "Whether the prohibition of drugs in Schedule IV (cannabis and cannabis resin, desomorphine, heroin, ketobemidone) should be mandatory or only recommended was a controversial question at the Plenipotentiary Conference." The provision adopted represents "a compromise which leaves prohibition to the judgement, though theoretically not to the discretion, of each Party." The Parties are required to act in good faith in making this decision, or else they will be in violation of the treaty.

(Wikipedia)