3. What will you do to reduce drug influenced driving?

3. What will you do to reduce drug influenced driving?


TOP Takeaway: Drug driving is already an issue. The current system used by police is seen as best practice, and will continue to improve as new evidence and tests become available. As long as usage rates do not significantly increase we would not expect to see an increase in drug driving. 

There is clear evidence from controlled laboratory trials that cannabis use reduces psychomotor performance, increasing the overall risk of accidents particularly while driving. This has been a key issue raised in international consultation over cannabis reform. However, due to the current prevalence of cannabis, impaired driving is not a new challenge. It is a criminal offence that exists today and is a challenge that must continue to be addressed, irrespective of how or when cannabis is legalised. The current system that is used by police is robust, and the best available measure until testing science is developed further[i]. Therefore, in terms of policy the policing of this issue should not significantly change.

Debate continues about the ideal (from a policy perspective) blood and/or saliva levels to indicate marijuana intoxication while driving. However a saliva test cannot show impairment only the presence of a drug, which does not necessarily imply impairment. Innovations are in development in various jurisdictions in the United States and abroad, including defined levels for impaired driving and how these can be analysed by saliva sampling, but as mentioned, these are not yet considered robust.[ii] In comparison, the appropriate levels deemed safe to drive for alcohol took years to develop, it is hoped that as discussions about cannabis become more common, and its legal status changes, this testing can be developed at a much faster rate.

TOP advocates continuing the current system. Drivers that have given reason to be considered under the influence, such as through driving erratically, will be given a roadside impairment test, and if failed will be blood tested. Evidence shows that the overwhelming majority – 95 percent of those who were asked for a blood specimen – tested positive for drugs, indicating police are judging driver behaviour well and not over-referring drivers.[iii]


[i] http://www.transport.govt.nz/legislation/acts/qasdrugimpaireddrivinglaw/

[ii] http://www.rand.org/pubs/research_reports/RR864.html

[iii] http://www.transport.govt.nz/legislation/acts/qasdrugimpaireddrivinglaw/