"The identification of cannabis as a potentially dangerous psychoactive substance did not, however, prevent a substantial number of these enquiries to explore the issue of whether current legislation reflected the real dangers posed by cannabis. Already in 1944, the La Guardia Committee Report on Marihuana concluded that ‘the practice of smoking marihuana does not lead to addiction in the medical sense of the word’ and that ‘the use of marihuana does not lead to morphine or heroin or cocaine addiction’ (Zimmer and Morgan, 1997). In 1968 the Wootton Report stated that ‘the dangers of cannabis use as commonly accepted in the past and the risk of progression to opiates have been overstated’ and ‘cannabis is less harmful than other substances (amphetamines, barbiturates, codeine-like compounds)’. A similar conclusion was arrived at 34 years later in 2002 when the Advisory Committee on Drug Dependence proposed the reclassification of cannabis from Class B to Class C (enforced by law in 2004 and confirmed in 2005). These views were reiterated by other enquiries, such as the Baan Committee in the Netherlands, which affirmed in 1971 that ‘cannabis use does not lead directly to other drug use’ (16) or by the US National Commission on Marihuana and Drug Abuse, which in 1973 stated that ‘the existing social and legal policy is out of proportion to the individual and social harm engendered by the use of the drug [cannabis]’ (17). The Canadian Le Dain Commission saw ‘the UN Single Convention of 1961 as responsible’ for such a situation which ‘might have reinforced the erroneous impression that cannabis is to be assimilated to the opiate narcotics’. The same commission, however, suggested that the UN Convention did ‘not prevent domestic legislation from correcting this impression’ (18)."
EMCDDA (2008), "A cannabis reader: global issues and local experiences," Monograph series 8, Volume 1, European Monitoring Centre for Drugs and Drug Addiction, Lisbon.