The Governments of several States have passed legislation allowing patients suffering from certain health conditions (such as terminal cancer, epilepsy and neurological illnesses) to use cannabinoids and cannabis to treat the symptoms of their illnesses (see box 1 for definitions of key terms). Some medical cannabis programmes have had an adverse impact on public health because they have not been effectively regulated in line with the international drug control treaties, resulting in the diversion of cannabis to non-medical use. In several countries, poorly regulated medical cannabis programmes and the associated lower perception of risk may have contributed to the legalization of non-medical cannabis use, contrary to the international drug control treaties.
Cannabis is included under Schedules I and IV of the Single Convention on Narcotic Drugs of 1961 as amended by the 1972 Protocol1 because it produces dependence and has adverse public health consequences (see section E below). Those consequences include injuries in motor vehicle crashes, mental illnesses such as psychoses, impaired cognitive and educational performance, disrupted adolescent development and adverse effects on fetal development. Cannabis use that begins during adolescence can damage the developing brain at a time of increased vulnerability.
The main cannabinoids with psychoactive properties, namely, THC and its isomers and their stereochemical variants, are included in Schedule I of the Convention on Psychotropic Substances of 19713.