The reversals of the “gateway” sequence are particularly noteworthy. It is an empirical fact that a substantial proportion of drug users initiate their drug involvement with illicit rather than licit drugs or use “hard” drugs before marijuana (Golub and Johnson, 2002; Kandel and Yamaguchi, 2002; Mackesy-Amiti et al., 1997; Tarter et al., 2006). When non-US samples are taken into account, as in the large multi-national study by Degenhardt et al. (2010), the “gateway” sequence and its “violations” can be even more clearly seen as functions of the frequency of cannabis use in the population. For instance, in Japan, where cannabis is used by only 4.5% of the 18–29 year old population, while use of other illicit drugs is 4.8%, cannabis is not used first by a staggering 83.2% of the users of other illicit drugs, “violators” of the “gateway” sequence. The overall level of illicit drug use does not depend on access to the purported gateway substances, whether alcohol/tobacco or cannabis, as would be expected if the GH were true. The “gateway” role of alcohol is also refuted by the
