Volume 50, Issue 6, June 2021
Delta-9-tetrahydrocannabinol (THC) impairs driving performance and can increase crash risk. These effects are more pronounced in people who use THC occasionally and can last for up to eight hours with oral THC products. There is no evidence that cannabidiol (CBD) impairs driving. Patients using THC-containing products should avoid driving and other safety-sensitive tasks (eg operating machinery), particularly during initiation of treatment and in the hours immediately following each dose. Patients may test positive for THC even if they do not feel impaired, and medical cannabis use does not currently exempt patients from mobile (roadside) drug testing and associated legal sanctions.
Dalgarno Comment: The term ‘behaviourally tolerant’ when used in a clinical report about drug driving issues always raises a red flag.
The research affirms, not only what we instinctively know, but what decades of long fought for science has told us, that intoxicants impair motor and cognitive abilities. Increasing the potential of turning a vehicle into a weapon against public safety.
The fight to have BAC limits introduced was a long and difficult one, but such measures are instrumental in reducing road tolls and associated harms. The increasing push to normalize cannabis use and introduce it to the currents of trade, even if in ‘medicinal’ contexts, means an increasing incidence of people choosing to drive whilst ‘medicated’. We understand from long established research that airline pilots (image below) even after one low dose THC ‘joint’ failed on many task matrices.
The notable concern in the report was the reference to users ‘perception’ of their ability to drive with THC in their system. When drug user self-assessment becomes to diagnostic indicator of ability we have a serious problem.
It may be a factor to consider, but when the following statement: ‘Behavioural Tolerance’ is added to the criteria for evaluation, we have regressed, not only in thinking, but in methodology. It is like going back to the pre-RBT (Random Breath Testing) days of evaluating driving capacity whilst drunk. If one could ‘walk a straight line and stand on one leg’, then that individual was legally ‘capable’ of driving. Although you may have a BAC of .10 (twice the legal limit), if you can ‘prove behavioural tolerance’, then you can keep driving.
Intoxication and impairment cannot be left to subjective self-assessment, and very strict limits/penalties set on substances we know to diminish capacity and agency.)