International approaches to driving under the influence of cannabis: A review of evidence on impact.
There are knowledge gaps regarding the effectiveness of different approaches designed to prevent and deter driving under the influence of cannabis (DUIC). Policymakers are increasingly interested in evidence-based responses to DUIC as numerous jurisdictions worldwide have legally regulated cannabis or are debating such regulation. We contribute a comprehensive review of international literature on countermeasures that address DUIC, and identify where and how such measures have been evaluated.



The following databases were systematically searched from 1995 to present: Medline, Embase, PsycINFO, CINAHL, Sociological Abstracts, and Criminal Justice Abstracts. Hand searching of relevant documents, internet searches for grey literature, and review of ongoing email alerts were conducted to capture any emerging literature and relevant trends.



Numerous international jurisdictions have introduced a variety of measures designed to deter DUIC. Much interest has been generated regarding non-zero per se laws that set fixed legal limits for tetrahydrocannabinol and/or its metabolites detected in drivers. Other approaches include behavioural impairment laws, zero-tolerance per se laws, roadside drug testing, graduated licensing system restrictions, and remedial programs. However, very few evaluations have appeared in the literature.



Although some promising results have been reported (e.g., roadside testing), it is premature to draw firm conclusions regarding the broader impacts of general deterrent approaches to DUIC. This review points to the need for a long-term commitment to rigorously evaluate, using multiple methods, the impact of general and specific deterrent DUIC countermeasures.
Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, M5S 2S1, Canada. Electronic address: taramarie.watson@camh.ca.
Tara Marie
TM
Watson
Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, 33 Russell Street, Toronto, Ontario, M5S 2S1, Canada; Dalla Lana School of Public Health, University of Toronto, 155 College Street, Toronto, Ontario, M5T 3M7, Canada. Electronic address: robert.mann@camh.ca.
Robert E
RE
Mann
D001334:Automobile Driving / Q000331:legislation & jurisprudence; D002188:Cannabis; D000066448:Driving Under the Influence / Q000331:legislation & jurisprudence / Q000517:prevention & control*; D006801:Humans; D038622:Internationality / Q000331:legislation & jurisprudence; D008385:Marijuana Smoking / Q000453:epidemiology* / Q000331:legislation & jurisprudence / Q000517:prevention & control*; D015813:Substance Abuse Detection / Q000331:legislation & jurisprudence / Q000379:methods*
Cannabis/marijuana; Driving; Drugs; Law; Policy