Cannabis and Hard Drugs: is there a supply-side gateway effect?

Abstract

The gateway hypothesis holds that cannabis consumption increases the risk of becoming a hard drug user. One possibility is that purchasing cannabis from street dealers who also have an incentive to sell hard drugs may influence cannabis users to migrate to hard drugs. We investigate the policy implications of this, examine US and UK evidence on the prevalence of co-supply of cannabis and hard drugs in the dealer population and analyse US and UK survey data on perceptions of drug availability. We find significant evidence for an access gateway in the US but not the UK.