Cannabis can be both addictive and harmful.
Our understanding of the precise extent and nature of the health implications of recreational cannabis use is developing but, at this stage, there is a great deal of uncertainty. On the eve of the first legal retail sales of recreational cannabis in Canada, the Canadian Medical Association Journal published an editorial which referred to legalisation as: a national, uncontrolled experiment in which the profits of cannabis producers and tax revenues are squarely pitched against the health of Canadians.1
The World Health Organisation recognises addiction rates of 1 in every 9 adults that uses cannabis. This rate of addiction is significantly higher in teenagers, the very age group most susceptible to its harmful effects. Currently, there is scientific uncertainty regarding the causality between cannabis use and the onset of conditions such as psychosis or diminished cognitive function. Nevertheless, there is a compelling body of correlational evidence, spanning 20 years and multiple jurisdictions, that heavily suggests that there is a such relationship. This is particularly pronounced in frequent and younger users. The existing law does mitigate the risk that cannabis poses. Although there has been a slight up-lift in recent years, cannabis consumption has been falling for nearly 20 years in the UK. A great many people do take the law seriously and, to many, the law continues to deter them from using a harmful substance.