The price of street heroin and cocaine decreased by more than 80 per cent in the US and Europe in the past 20 years. Despite a huge investment by the US in drug law enforcement, northern Mexico has descended into a drug cartel battlefield, driven by the demand for illicit drugs within the US. At the local level, our young people can and do purchase illicit drugs with ease and generally with impunity. If this is an effective policy at work, I am not sure what failure would look like.

After 33 years, I can no longer ignore the evidence on drugs