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In 2018, when cannabis became legal for recreational consumption by Canadians of legal age, impaired driving became a bigger problem. According to a 2019 survey by Public Safety Canada, 26% of cannabis users who had a valid driver’s license reported driving a vehicle within two hours of using cannabis. Of course, doing so puts not only the consumer/ driving at risk because anyone potential passengers as well as other drivers. Because of this, there are laws in Canada about driving under the influence of cannabis. 

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How Does Cannabis Affect Driving? 

Cannabis makes you a worse driver. It can make you less alert, make it harder to concentrate and limit your short-term memory. Your driving will become more unpredictable, and your decision-making process is slower. It can also change your perception of time and distance, making you think that something is closer or further away than it is or will take more or less time to reach an object or location than it actually will. Your chances of getting into an accident or harming someone when you are not sober and fully alert increase significantly when you’re under the influence of cannabis.

Combining cannabis with alcohol before you drive is even worse. Your driving abilities, including your reaction time and concentration, will become even more impaired if you are under the influence of both THC and alcohol.

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How Does Law Enforcement Know If You’ve Been Driving High?

Even without testing you, law enforcement can suspect if you’ve been driving high because you may be showing both physical and behavioural signs. Showing these signs doesn’t prove that you’ve been driving high, but it can make law enforcement suspect that you are impaired.

If you’ve consumed cannabis, there may be a smell, and you may have a rapid heart rate, shallow breathing, dry mouth, and red, watery, or glassy eyes. Your judgement may also be impaired, and you could have poor coordination, paranoia, a delayed reaction time, and unfocused states.

Law enforcement can confirm their suspicions by testing you to see if you’ve consumed THC.

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Police Test For Cannabis Use In Drivers

Police officers can test you on the roadside if they suspect that you are using cannabis before driving.

Currently, Ontario, PEI, Manitoba, Saskatchewan, Nova Scotia and Alberta have a device that tests your saliva for THC. This device is called the Draeger DrugTest 5000.  Police officers may also test for cannabis through the standardized field sobriety test (SFST) or an oral fluid test. If you fail either of these tests, they could bring in a drug recognition expert or get a blood sample from you for testing. Please note, that according to Madd, the standardized field sobriety test and the saliva test cannot be used to convict you in a trial, but the blood test or drug recognition expert could be.

Check out if cannabis use affects your ability to get life insurance.

Consequences Of Cannabis Impaired Driving

Driving while under the influence of cannabis is covered under both federal and provincial/territorial law. 

Under federal law, if you have between 2 and 5 nanograms of THC per millilitre of your blood within two hours of driving, you can receive up to a $1,000 fine as a summary conviction criminal offence. More than 5 nanograms of THC per millilitre of blood can net you a minimum of a $1,000 fine for your first offence, a minimum of 30 days imprisonment for your second offence, and a minimum of 120 days imprisonment for your third or subsequent offences.

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You can also face similar penalties if you have both THC and alcohol in your system. Under federal law, if you have more than 50 milligrams of alcohol per 100 millilitres of blood plus 2.5 nanograms of THC per millilitre of blood, you will face the same penalties as you would for having more than 5 nanograms of THC per millilitre of blood.  

For offenses that cause bodily harm, you could be sent to prison for a maximum of 10 years and up to a lifetime if you cause death. 

Each province and territory may also have laws that inflict stricter penalties on offenders. These penalties include fines, prison time, license suspension, vehicle seizures, or education courses.

Check out the winter tire laws in Canada.

Ways To Avoid Driving While High

Instead of driving while high, you should find another way to get where you need to go. Getting someone else to drive you, like a friend, family member, designated driver, taxi driver, or rideshare driver is a great way to avoid impaired driving. You could also take public transit. You might also want to consider staying the night somewhere safe where you won’t have to drive, like a friend’s house, hotel, or Airbnb. 

Frequently Asked Questions

How long do I need to wait before driving after smoking a joint?

It really depends on a number of factors – how much you’ve smoked, how potent the cannabis is, if you’ve also consumed alcohol, and how frequently you consume cannabis, just to name a few. Generally, however, you should wait a minimum of four to six hours after smoking a joint before you get behind the wheel. With that in mind, it’s best to simply not get behind the wheel at all if you’re going to consume cannabis. 

Can you drive while on CBD?

Yes, you can drive while on CBD. Although CBD is a component of cannabis, it doesn’t give you a high as THC does. Cannabis DUI tests are for THC, so you shouldn’t test positive for THC after consuming CBD products.

What’s worse, driving while drunk or high?

Both driving while drunk and driving while high are illegal and potentially deadly. Because both cannabis and alcohol affect people differently, it’s hard to say whether someone’s driving is worse when they’re drunk or when they’re high.

Can I fail the test hours or days after consuming cannabis?

According to Madd, while traces of cannabis can be found in your system after quite some time, you shouldn’t worry too much about failing the oral fluid test unless you recently consumed cannabis. The reason being, the roadside oral screening test is set to trigger at  25 nanograms of THC per millilitre in a person’s oral fluid, which is a lot higher than the driving limits. This is done so that only those who have recently used or are heavily impaired get caught. 

Bottom Line

Cannabis affects your driving ability, and driving under the influence can lead to accidents or worse. That is why there are laws in Canada for driving high. Besides the physical and behavioural signs you show when you’re impaired, police officers can test you if they suspect you’ve been driving while impaired. Failing any tests they give you can result in fines, prison time, and more. To keep everyone on the roads safe, don’t drive high, and if you’ve consumed cannabis recently, find a way to get home safely without driving yourself.

Matthew Taylor avatar on Loans Canada
Matthew Taylor

Matthew joined the Loans Canada writing team in 2021 while was finishing up a Bachelor's degree at the University of Saskatchewan. It was there that he discovered his love of writing. His work has appeared in several publications, including the Canadian Student Review and In his spare time, Matthew enjoys reading, geocaching, and spending time with his family and pets.

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