Medical Cannabis and Driving


Australian Law Needs to Catch Up With Medicinal Cannabis Usage

By Jessica Kindynis As Australian medical cannabis patient numbers rapidly grow, there is a great need for updated and cohesive laws regarding driving and cannabis. With medical and adult-use increasing in prevalence around the globe, researchers are racing to assess the impact of cannabinoids on driving. However, much like the wide-ranging pharmacological actions of medical cannabis, regulating and assessing its impact on driving is complex.

What Australian Drivers Need to Know While Taking CBD and THC Medications

Across all Australian states, it is illegal to drive with any amount of THC in saliva, blood or urine. Yet, despite widespread use of CBD in the form of CBD oil for example, the legality behind taking CBD-only medications and lawfully driving continues to be a grey area. Recommendations state that medical cannabis patients should discuss with their prescribing doctor how to safely and legally drive, whilst having a medical cannabis prescription.    While CBD has no psychoactive effects, it can cause drowsiness and lower blood pressure and for a few people this may impact their capacity to drive. It is crucial for patients to know the ratio of CBD to THC in their prescribed formulation, as even the purified CBD products can contain minuscule amounts of THC. While tiny concentrations of THC may not show up in a roadside drug test, it may appear on a blood test and it does not necessarily provide an “all-clear” for patients operating a vehicle or other machinery while taking product labelled as CBD only.    So far it seems, NSW is the only state that the law has explicitly noted information about CBD and driving, saying that:  “Patients taking cannabidiol-only medicines can lawfully drive, as long as they are not impaired”. Capacity to drive and level of impairment in most government guidelines are said to be determined by the prescribing doctor, who should have a firm idea of what effects the medicine will have on the patient. However, effect and duration of impairment vary widely depending on the route of delivery and metabolism of the individual, this makes assessing and measuring impairment to driving in a standardised fashion particularly difficult.   Under the Road Transport Act 2013 driving with any detectable amount THC is against the law in NSW (this is consistent with other states), and no exclusions are named for prescribed medicines. Considering THC can stay in circulation for beyond 30 days this poses a huge risk for medical cannabis patients still requiring the use of their car, even if they are not impaired by their medication.   As a society, we are accustomed to the use of breathalysers to detect blood alcohol levels and saliva tests for cannabis and other drugs. While such tests seem interchangeable they are in fact very different. Blood alcohol measures can be directly linked with driving impairment and are relatively accurate at deducing the time of consumption when extrapolated back in time. By comparison, the presence of THC in a roadside saliva test, unlike blood alcohol, does not offer a definitive measure of physical or cognitive impairment.   Blood tests providing toxicology report on cannabinoids, including metabolites of degraded THC are more accurate at determining the subjective high and probable impairment. Despite this, cannabis is metabolised at varying rates by different individuals and is strongly impacted by the route of administration, therefore determining the specific time of impaired driving abilities is still approximate.  In late 2018, industry experts Professors Kylie O’Brien and Ian Brighthope released a position paper addressing many of the main concerns for medical professionals and regulators regarding medical cannabis. In this, they noted the subjective nature of being fit to drive with THC in the body and highlighted that potential patients are concerned to use medical cannabis fearing they would be defying the law. The paper recommends that Australia take a similar stance to Canada, whose cannabis driving laws have been refined over the past decade. This would mean drug-impaired driving would remain an offence however, medical cannabis patients would be exempt should they be deemed fit to drive via Standardised Roadside Sobriety Testing. Police would be trained in specific ways to detect impairment and specialised drug recognition experts could be utilised to confirm fitness to drive.  As the Australian medical cannabis landscape continues to expand, regulators must quicken their step to realign laws with a growing number of citizens who will have cannabis in their system. Clear and specific markers of behavioural and motor deficits should be implemented for patients, to differentiate them from unsafe cannabis influenced drivers.    

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