A majority of Australians who use cannabis for medical reasons said roadside drug testing put them off driving after consuming it — but more than half also said it affected how they managed their treatment, according to new research.
The study, carried out by Australian researchers and published in the journal Transportation Research Part F, drew on surveys from 2,609 Australians who had driven in the past 12 months and used cannabis to manage a medical condition.
According to the findings, 69% of participants said roadside drug testing discouraged them from getting behind the wheel after using medical cannabis, while 51% said it either stopped them from using cannabis altogether or changed the type of product they chose.
Among those surveyed, 73% identified prescribed medicinal cannabis as their primary source, while around 28% reported having driven under the influence of cannabis at some point during the year.
Of those who admitted to drug-affected driving, the most frequently cited reason was a belief that they were not impaired, with 69% giving this explanation.
Smaller shares said they drove under the influence because they had no other transport available (25.7%), or because they felt impaired but judged themselves still capable of driving safely (21.6%).
The research found that people who consumed cannabis more often throughout the day — particularly those using inhaled products such as smoked flower — had higher odds of driving while under its influence, as did those who continued to obtain cannabis through illegal channels.
In contrast, patients who believed cannabis affected their driving ability, or who said roadside testing deterred them, were considerably less likely to drive while impaired.
Although only 10% of respondents had been stopped for roadside drug testing in the previous year, the rate of positive tests and convictions among that group (15.1%) was low.
The results arrive as pressure mounts in New South Wales to overhaul drug-driving laws for patients prescribed medicinal cannabis, with the state government saying it needs more evidence before it will consider introducing a medical cannabis driving defence.
Tasmania already provides a legal defence for medicinal cannabis patients who hold a valid prescription and are not impaired, and Victoria has given magistrates the discretion to avoid cancelling a driver's licence — though in both states, driving with detectable THC in the system remains an offence outside those specific provisions.
