This paper gives a brief history of how medical and recreational cannabis use have been legalised in the USA and describes how recreational cannabis use is being regulated in 8 states in the USA, Uruguay and Canada. I explain why it is still too early to evaluate the full impacts of cannabis legalisation in the USA, describe the increasing potency of cannabis products, innovations in cannabis products and how they are marketed, and in how cannabis businesses are financed. I explain why many of these developments raise concerns about the future public health impacts of cannabis legalisation by affecting patterns of cannabis use after legalisation. I use the history of policy experiences with alcohol and tobacco to make some cautious predictions about the likely future impacts of cannabis legalisation on public health.
Wayne Hall is a Professorial Fellow at the Centre for Youth Substance Abuse Research at the University of Queensland and the Queensland Alliance for Environmental Health Sciences. He has been: a Professor at the National Addiction Centre, Kings College London (2014-2019); Director of CYSAR (2014-2016), NHMRC Australia Fellow, the University of Queensland Centre for Clinical Research (2009-2014), Professor of Public Health Policy, School of Population Health (2005-2009), Director of the Office of Public Policy and Ethics, Institute for Molecular Bioscience (2001-2005) and Executive Director of the National Drug and Alcohol Research Centre (1994-2001). He has advised the World Health Organization on the health effects of cannabis use; the effectiveness of drug substitution treatment; the contribution of illicit drug use to the global burden of disease; and the ethical implications of genetic and neuroscience research on addiction.