Medical Cannabis Driving Inquiry Reveals Impairment Measure Key As NSW Law Change Considered

Can you stand on one leg with your eyes closed?

It was one of the tests suggested at a New South Wales parliamentary inquiry in Sydney into whether a motorist was fit to drive after consuming medical cannabis.

The inquiry heard from a range of experts on a Greens bill designed to protect medical cannabis patients in NSW from drug driving charges.

The determination of impairment has become a key issue in the debate.

Current New South Wales laws, introduced in 2007, mean a motorist can be charged if a trace of the psychoactive component of cannabis (THC) is detected in their system.

This can happen after a blood test or a roadside saliva test.

A DrugWipe saliva test is used to detect the presence of cannabis, cocaine and methamphetamines.(ABC North Shore: Bruce MacKenzie)

The federal government legalized the use of medical cannabis in 2016, but NSW law remains the same.

Dr Joel Wren, of the Society of Cannabis Clinicians, told the inquiry today that the current laws are ‘archaic’ and ‘nothing short of discrimination’.

He said driving laws surrounding medical cannabis should be consistent with other prescription therapies such as opioids.

“We prescribe these drugs widely every day to many Australians and tell them it’s okay to wait a bit if you feel low, some people metabolize these drugs differently,” Dr Wren said.

Disability, a key issue

But the Standing Committee on Law and Justice has been told that it may be difficult to determine the level of impairment of a cannabis user.

Dr Danielle McCartney, of the University of Sydney’s Lambert Initiative for Cannabinoid Therapies, told the inquest that she had done extensive field work using driving simulators and computerized testing of cognitive functions.

“Obviously all of this is impractical at the roadside,” she said.

“There are of course field sobriety tests, which are used internationally to identify people who are unsure of driving.”

Professor Iain McGregor of the Lambert Initiative said the traditional test of having a motorist walk in a straight line did not work well for cannabis users.

“Cannabis users seem to be able to walk the straight line quite well,” he said.

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Can you stand on one leg with your eyes closed? This is a proposed new sobriety test(ABC North Shore: Bruce MacKenzie)

Dr Thomas Arkell, of Swinburne University, told the inquest he had reservations about the test.

“Some people find it very difficult anyway,” he said.

“Particularly in older people when your balance tends to deteriorate, especially if you have hip or treble issues.”

The inquiry heard that 180,000 applications for the use of medical cannabis had been approved by the Therapeutic Goods Administration as of October 12, 2021.

The number of active patients in Australia in September last year was estimated at 70,000.

Debate on the risk of accident

A submission to the NSW Government inquiry suggested that the presence of THC in a driver’s system increased their risk of a crash by 50%.

Professor Lambert disputed that figure, but acknowledged that the data was complex.

“What they call the odds ratio is about 1.1 to 1.4 if you’re acutely intoxicated with cannabis,” he said.

“In other words, it’s a 10 to 40 percent increased risk of an accident.

“That’s about the same as a blood alcohol concentration of 0.04 or 0.05, and it’s significantly less than what you would see with opioids or benzodiazapines or sedating antidepressants which are very widely prescribed.

Police test drivers for cannabis near Nimbin
Police take saliva swabs from drivers as part of roadside drug driving tests.(ABC North Shore: Gemma Sapwell )

Fatal accident factor?

But the inquiry was told the NSW government had no plans to change the law.

State Transportation Safety Chief Peter Dunphy said between 2016 and 2020 there were 253 fatal crashes involving drivers and passengers with THC in their systems.

“That’s about 16% of all fatal crashes and about one fatal crash per week,” he said.

“THC can affect the cognitive and motor skills necessary for safe driving.

“While it is true that much of the evidence for the effects of impairment comes from illicit THC use, there is still evidence that medical users of THC may be impaired for a period of time.

Mr Dunphy said cannabis was different from other drugs because there was no way to distinguish between medical and recreational use.

“Until there is clear evidence of the effects of medical cannabis on driving, the New South Wales government will continue to take a cautious approach,” he said.

Greens MLC Cate Faehrmann disputed the validity of the statistics cited in the government’s submission, suggesting that the fact that THC was present in a driver’s system did not necessarily make it a factor in a fatal accident.

The commission will present a report to parliament in early August.

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