Australia tests driving impairment levels with medical cannabis patients

Jun 5, 2024

The government in Victoria, Australia has announced its launch of a trial to research the effects of medicinal cannabis impairment on driving. The announcement comes after Australian researchers repeatedly urged the government to address issues regarding medicinal cannabis use and existing laws, and to determine whether existing drug-driving laws can be relied upon as an accurate measure of driver impairment.

Access to medical cannabis was legalized in Australia in 2016, permitting patients to access various cannabis products through prescriptions. In Victoria, there are two groups of medicinal cannabis patients, who are subject to different rules. Medicinal cannabis patients who use cannabidiol or CBD products are allowed to drive in Victoria if they are not impaired. Conversely, medicinal cannabis patients who take products containing tetrahydrocannabinol (THC) are not permitted to drive with any amount of THC in their system.

Currently, Victoria Police conducts random roadside drug testing using saliva tests for THC, with positive results prompting drug-driving charges.

The new trial by the government will seek to test just how impaired people with medicinal cannabis in their system are whilst driving. As part of the trial, which is the first of its kind and will take place in September with 70 participants who are medical cannabis patients, drivers will be taken around driving courses with an instructor at special closed road facilities.

“There is nowhere in the world that actually has got that standard way of measuring impairment through medicinal cannabis,” said Melissa Horne, Minister for Roads and Road Safety in her interview with ABC News. “It is a basic human right — we’ve got a legally prescribed drug, let us be able to measure what that looks like in a road safety environment.”

Currently, there is a lack of data regarding cannabis impairment and driving. In Canada, driving with THC levels of 2 nanograms (ng) per millilitre is considered an offence. According to one meta-analysis of research studies conducted in 2021, cannabis use increased the risk of crashes somewhere by 11-42%. Moreover, the study also found that the effects of THC on driving are typically “modest” and seem similar to the effects of low-dose alcohol consumption. However, the study also found that impairment may be more significant and potentially severe in individuals who are cannabis-naive or where cannabis is combined with alcohol or other impairment-causing drugs.