In the Australian cannabis landscape, driving laws are one of the most controversial topics. While we often compare cannabis to alcohol when talking about impairment and driving abilities, the current laws don’t take into account the way cannabis interacts with our bodies.
For this reason, Australia’s current cannabis and driving laws aren’t fair or reasonable.Because of this, it’s important that as a consumer of cannabis, you understand how cannabis and the different chemicals in cannabis impact your ability to drive.
We spoke with Tom Arkell to discuss the cannabis driving studies he’s conducted and to learn everything you need to know about cannabis’s effects on driving.
We’ve broken this topic into two articles. In these two articles, expert Tom Arkell explains:
- Does cannabis affect your driving abilities? | 00:18
- Does CBD reduce the impairment of THC? | 02:47
The legalities of cannabis, CBD oil and driving In Australia:
- Is it legal to drive while consuming medical marijuana?
- Can you drive (legally) while taking CBD oil?
- What is considered driving under the influence of cannabis?
- How long after consuming cannabis is it safe to drive?
- What are the driving laws in my state?
If you’re concerned about roadside tests or drug tests at work, check out our article, How long does cannabis stay in your system?
Does cannabis (marijuana) affect your ability to drive?
Yes. Cannabis consumption does affect your ability to dive.
However, the effects are not extreme. They are similar to what you might expect to see with a driver in a driver with a blood alcohol concentration of about 0.05, or within the legal limit.
One of the key differences between cannabis and alcohol is that the drivers who are under the influence of cannabis tend to be aware of it. They then often try to compensate for impairment by doing things like driving more slowly or more carefully. So, the research shows that the effects of cannabis on driving are quite different from the effects of alcohol.
Just because you’re conscious that you’re driving impaired, it doesn’t preclude the fact that you actually are impaired.
When driving you want to be as clear-headed as possible and you should not drive while impaired. Let’s take a deeper look at the research.
Does THC affect driving abilities?
Yes, THC does affect your driving abilities. Tom Arkell’s research in both simulator and on-road tests shows that THC can impair various functions that are important for driving.
THC impairs divided attention, processing speeds, how quickly you can take incoming information and respond appropriately. While peak impairment for cannabis tends to be between two and three hours, impairment on vaporised cannabis was seen up to four hours in the study.
Other studies confirm these findings.
In 2006, a study was created to help develop limits for driving under the influence of cannabis. Over 6 hours participants were then tested on three measures:
- Tracking performance (ie holding a straight line)
- Motor impulsivity (ie stopping at a red light)
- Executive function (ie general cognitive processes needed to achieve a goal)
In all three tests, the average performance of participants who had consumed THC significantly decreased.
Finally, in a 2017 literature review studied scientific research that looked at the relationship between cannabis and injury and death. The review looked at all-cause mortality, occupational injury, motor vehicle accidents, and overdose injuries and death.
The conclusion of the review was, “there is substantial evidence of a statistical association between cannabis use and increased risk of motor vehicle crashes.”
Does CBD or CBD oil affect your ability to drive?
The World Health Organisation (WHO) published a report on CBD. Regarding CBD and driving there are two noteworthy points:
- The WHO states, “At present no public health problems (e.g. driving under the influence of drugs cases, comorbidities) have been associated with the use of pure CBD.
- A study is cited which gave healthy participants 200mg of CBD orally which did not produce any impairments of motor or psychomotor performance.
Tom Arkell confirmed that, from a research perspective, it’s highly unlikely that CBD has an impact on driving. While his vaporised CBD trial in the Netherlands confirmed this, he also mentioned that there hasn’t been significant research done on higher doses of CBD via an oil.
Is there a difference between CBD oil or CBD vaporised?
It’s easier to get much higher doses of CBD via an oil than through smoke or vapour. Research shows that at very high doses, CBD can be sedating. There’re also plenty of examples of people using CBD to aid relaxation and sleep.
In this case, it may seem logical that high doses of CBD oil could impact your driving. The team at the Lambert Initiative is currently working toward a trial on higher doses of CBD via an oil.
The key takeaway here is that pure CBD oil is unlikely to have any impact on your motor skills; however, there isn’t enough research to say definitively. If you’re unsure of whether you should be driving, consult your doctor.
Driving abilities are impaired by cannabis
Based on the research it would seem that cannabis, particularly THC, does have an impact on your driving abilities and that using cannabis while driving increases the risk of crashing. It’s also important to note that everyone responds differently to cannabis and how long it takes for the effects to wear off. While there isn’t any sort of measure on how much, it’s clear that cannabis affects driving.
It’s apparent that more research needs to be done on cannabis and driving before we have any sort of standards for impairment like we do with alcohol.
Does CBD reduce the impairment of THC?
An Australian study published in 2019 looked at cannabidiol (CBD) and THC and impacts on driving and cognition. The study found that no matter what the ratio of CBD and THC, cannabis increased the amount of “lane-weaving.”
Interestingly, Tom Arkell’s study found that higher doses of CBD may impact your feeling of the ‘high’ for approximately the first half-hour, but that dissipates over the next hour. More importantly, the findings are that the CBD does not reduce impairment and in some cases can actually increase impairment.
One limitation to Tom’s study is that they have only reviewed a 1:1 ratio of CBD to THC. This does leave the possibility that much higher doses of CBD to THC could reduce impairment.
Cannabis and driving studies have proven that THC does impact your ability to drive. We also know that, at this stage, research shows that CBD doesn’t impact one’s driving abilities.
Remember that if people tell you taking CBD will reduce your impairment, they aren’t exactly correct. CBD may make you feel less impaired for a short period of time, but it doesn’t reduce impairment.
Now that you understand the impact of cannabis on driving, you may want to learn more about how long after cannabis consumption you can drive or how long cannabis stays in your system with relation to roadside tests.
Regardless of your situation or condition, please do not drive while impaired.