Preventing cannabis users from driving under the influence of cannabis.

Face-to-face, structured interviews were conducted with 320 recent cannabis users in New South Wales, Australia to assess the likely deterrent effects of (a) increasing the certainty of apprehension for driving under the influence of cannabis (DUIC) and (b) doubling the severity of penalties for DUIC. Participants were presented with a drug-driving scenario and asked to indicate their likelihood of driving given that scenario. The perceived risk of apprehension and severity of punishment were manipulated in each scenario to create four different certainty/severity conditions and participants were randomly allocated to one of these four groups. A subsidiary aim was to assess the likely impact of providing factual information about the accident risk associated with DUIC. Recent drug drivers who felt at low risk of accident when DUIC were asked to rate their willingness to drive if convinced that it was dangerous. The results suggested that increasing the certainty but not severity of punishment would produce reductions in cannabis-intoxicated driving among recent cannabis users. Providing factual information about the risks associated with DUIC would appear to have little impact on drug-driving rates among this population.