Cannabis and driving: new briefing presents questions and answers for policymaking

Frequently asked questions on cannabis use and road safety

What is the impact of cannabis use on driving? Do edible and smoked cannabis products affect drivers in the same way? How should the law deal with drivers who take cannabis for medical reasons? These are among the questions addressed today in a new policy briefing on cannabis and driving, published by the EU drugs agency (EMCDDA) and the Canadian Centre on Substance Use and Addiction (CCSA).

With cannabis policy evolving internationally (1), cannabis-impaired driving has become an increasingly relevant issue. The new briefing aims to provide those concerned with policy in this field with an overview of the latest knowledge and developments.

The briefing draws on the evidence presented at the Third international symposium on drug‑impaired driving, held in Lisbon on 23 October 2017. The event was a collaborative initiative of the EMCDDA, the CCSA, the US National Institute on Drug Abuse (NIDA) International Program and the New Zealand Drug Foundation. Over 100 participants attended the event, which brought together researchers, practitioners and policy experts from over 30 countries.

The briefing answers 15 questions grouped in four key areas addressed at the symposium:

  • Challenges for regulatory models
  • Drug screening, testing and detection
  • Preventing cannabis-impaired driving
  • Future perspectives for research and monitoring.

The briefing looks at the usefulness of biological and behavioural tests in assessing cannabis-related impairment as well as the challenges they present. It describes how the effects of smoked cannabis differ from those of edible cannabis and discusses the complexities arising when drivers mix substances (e.g. cannabis and alcohol). The briefing also considers the various options available for responding to cannabis-positive drivers and the need to complement penalties with education countering young people’s misconceptions about the levels of risk involved.

With cannabis use no longer illegal in some jurisdictions (be this for medical or recreational purposes), laws penalising cannabis-positive drivers may become similar to those penalising alcohol-positive drivers. For example, many countries are working towards laws that establish maximum permissible blood‑drug limits. As in the case with alcohol, these laws would mean that any driver ‘over the limit’ would be committing an offence and there would be no need to prove physical impairment. Whatever approach is chosen, ongoing evaluation will be crucial.

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