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Proposal for ‘cautious path’ forward for changing cannabis laws by Otago researcher

Clocktower.

Friday, 18 January 2019

Joe Boden image
Associate Professor Joseph Boden

Amid the ongoing debate on legislation for recreational use of cannabis, an Otago researcher proposes a cautious path forward for changing cannabis laws in New Zealand that aims to reduce cannabis-related harm.

Associate Professor Joseph Boden from the Department of Psychological Medicine at the University of Otago, Christchurch, has a research interest in the use of cannabis and has specifically investigated the use of cannabis among participants in the Christchurch Health and Development Study, a study following the lives of 1265 children born in Christchurch in 1977. By age 35, almost 80 per cent of the participants had reported using cannabis at some point in their lives.

In an editorial in the latest issue of the New Zealand Medical Journal today, Associate Professor Boden says to date most of the debate on changes to cannabis law imply it is a relatively harmless drug and that cannabis law change will only have beneficial consequences. However, both he and co-author of the editorial, the late Emeritus Professor David Fergusson, former director of the Christchurch Health and Development Study disagree.

“We would argue that, on the basis of evidence generated by longitudinal studies based in New Zealand, both assumptions are incorrect,” their editorial states.

What they propose is development of laws and policies that both discourage the use of cannabis and avoid criminalising recreational users of the drug. The key elements of their policy are:

  • Simple possession of cannabis by those over 18 would be decriminalised, as would supply of small amounts to adults, as recommended by the recent Mental Health Inquiry.
  • Penalties for the supply of cannabis to those under 18 would be increased.
  • Investments in mental health services for those with cannabis use disorder and cannabis-related conditions would be increased, again in line with the recent Mental Health Inquiry.

Professor Fergusson died in October last year, but he and Associate Professor Boden wrote the editorial prior to his death. Associate Professor Boden explains their reasoning is based on their research which shows resoundingly that cannabis use by participants in the Christchurch study is associated with educational delay, welfare dependence, increased risks of psychotic symptoms, major depression, increased risks of motor vehicle accidents, tobacco use and other illicit drug use and respiratory impairment.

At the same time, evidence from the study suggests the prohibition of cannabis is also a cause of some harm with males and Māori participants having higher rates of arrest and conviction for cannabis-related offences. Furthermore, the analysis showed that cannabis use did not decrease following this, suggesting prohibition generally failed to reduce cannabis use among participants.

“Given this context, the most prudent course of action for New Zealand to follow is to develop policies which eliminate the adverse effects of prohibition while at the same time avoiding the possible adverse consequences of full legislation,” their editorial states.

They highlight recent research reviewing changes in both medical and recreational cannabis laws in the United States that has shown cannabis legislation has increased the use of cannabis and cannabis-related harm. While cannabis use among adolescents has not increased, both cannabis use and cannabis-use disorders increased among adults. There was also evidence of increases in cannabis-related emergency department visits, driving under the influence of cannabis and accidental exposure to cannabis in children.

View an opinion piece by Associate Professor Boden that highlights his research

Read the obituary of Emeritus Professor David Fergusson

For further information, contact:

Associate Professor Joseph Boden
Department of Psychological Medicine
University of Otago, Christchurch
Tel +64 3 372 6744
Email joseph.boden@otago.ac.nz

Liane Topham-Kindley
Senior Communications Adviser
Tel +64 3 479 9065
Mob +64 21 279 9065
Email liane.topham-kindley@otago.ac.nz