The future of international drug control treaties is in question because of recent treaty-violating decisions to legalise non-medical cannabis use in Canada, the United States and Uruguay.
In 2014 Professor Hall wrote a 20-year review of cannabis research which attracted worldwide headlines.
“If decriminalisation is the way of the future, a cautious approach to policy reform needs to be considered, involving trialling and evaluating the effects of incrementally more liberal drug policies,” Professor Hall said.
“We do not want to replicate with cannabis the adverse public health effects of allowing the free promotion and widespread use of alcohol and tobacco.
“There is strong public support for medical cannabis use in Australian surveys, often in ignorance of the very modest evidence on the effectiveness and safety of medical use.
“The policy challenge for governments is to find ways of making cannabis products available for medical use without replicating experience in California where ‘medical use’ very broadly defined, was used to create a de facto legal market for non-medical cannabis use.
“It is important that policies minimise adverse effects of regular cannabis use such as dependence and the much poorer life outcomes of users who initiate cannabis use in their mid-teens and use daily during their early 20s.”
The international drug control treaties endorsed by most member states of the United Nations (UN) prohibit non-medical use of amphetamines, cannabis, cocaine and heroin.
The aim of the treaties is to reduce the harmful use of prohibited drugs and facilitate access to these drugs for medical and scientific purposes.
Critics claim that the treaties have failed to tackle non-medical use of prohibited drugs and have justified policies that conflict with UN human rights treaties by incarcerating large numbers of drug users.
Professor Hall made several suggestions in a study published this month by the scientific journal Addiction.
The paper outlines types of policies that nations could adopt to address the different types of harm that different illicit drugs cause to users and others.
Cannabis policy changes require treaty change, while others could be accomplished by more ‘flexible interpretations’ of treaty provisions by member states and UN agencies.
“Cannabis is the strongest candidate for national policy experiments on different ways of regulating its sale and use, as is happening in the USA, Uruguay and Canada,” Professor Hall said.
“Rigorous evaluations of these experiments will be useful for other countries considering legalising cannabis for adult recreational use.”
The University of Queensland