Most Australians using cannabis for medical purposes reported that roadside drug testing deterred them from driving after use, but more than half said it also influenced their treatment decisions, according to a study.
The study, conducted by Australian researchers and published in the journal Transportation Research Part F, surveyed 2,609 Australians who had driven in the previous 12 months and used cannabis for a medical condition.
Findings showed that 69% of respondents said the presence of roadside drug testing discouraged them from driving after medical cannabis use, while 51% said it deterred them from using cannabis at all, or impacted the type of product they used.
Of the respondents, 73% said prescribed medicinal cannabis was their main source of cannabis, while approximately 28% reported driving under the influence of cannabis during the year.
Among those who reported driving under the influence, the most common reason was believing they were not impaired, cited by 69% of respondents.
Smaller proportions said they drove under the influence due to a lack of alternative transport options (25.7%), or because they believed they were impaired but still capable of driving safely (21.6%).
The analysis found higher odds of driving under the influence among people who used cannabis more frequently throughout the day, particularly those using inhaled products such as smoked flower, as well as those who continued to source cannabis illicitly.
By contrast, patients who believed cannabis impaired driving, or who reported being deterred by roadside testing, were significantly less likely to drive while impaired.
While only 10% of respondents had been tested at the roadside in the past year, the rate of positive tests and convictions among those tested (15.1%) remained low.
The findings come amid calls in New South Wales to reform drug-driving laws for prescribed medicinal cannabis patients, as the government continues to seek further evidence before considering a medical cannabis driving defence.
Tasmania provides a legal defence for unimpaired medicinal cannabis patients with a valid prescription, while Victoria allows magistrates discretion not to cancel a licence – although in both states driving with detectable THC remains an offence in the absence of those conditions.