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Understanding the Rules, Regulations and Developments in Cannabis use in Canada

Kimball Law By: Kimball Law August 15, 2019 no comments

Understanding the Rules, Regulations and Developments in Cannabis use in Canada

Recreational cannabis legalization in Canada. A huge maple leaf made from dry weed, leant against the rock. The Canadian emblem incorporated into the mountain landscape, over the sunset background.

With the decriminalization and subsequent legalization of marijuana, there has been a great desire to introduce laws and other regulations surrounding the appropriate use of cannabis. In particular, lawmakers, public interest groups and the public in general have been calling for appropriate and fair legal limits for driving under the influence of cannabis. While the government has delivered on this by recently passing legislation, the methods of assessing impairment and THC content (the primary psychoactive ingredient in cannabis) have been heavily scrutinized. 

At the moment, it is an offence to drive with 2 nanograms (one billionth of a gram) of THC per millilitre of blood. Legal consequences vary based on the following factors: 

  1. how much THC is present in your system;
  2. how many times one has been charged with this offence; 
  3. the additional presence of alcohol; and 
  4. whether ‘driving high’ led to any injury or death. 

Legal penalties range from monetary fines below $1,000 to life sentences in prison in the event of impaired driving causing death. Because of the drastic consequences that marijuana can have on a driver and others on the road, it’s vital that effective and reliable methods of measuring impairment and THC concentration be developed and used.

What is cannabis and what makes it impair driving?

  • Before beginning, it is useful to understand the components of cannabis and the effects they have on an individual.  When marijuana is smoked or ingested, there are a variety of compounds that influence your body in different ways. The two primary chemicals in marijuana are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the main psychoactive component in marijuana, while CBD has no psychoactive compounds. Often times, medical marijuana contains a higher CBD concentration so as not to experience the “high” as much, while still aiding with things like pain and sleep. Recreational marijuana, which often contains greater amounts of THC, is associated more with getting users high. It is important to distinguish between these because THC is the main cause of concern among law enforcement as it is commonly linked to increased impairment. Employers are also concerned with THC content in their employees and want to be able to use appropriate methods to administer THC tests, especially if their employees must operate heavy machinery. The main impairments associated with marijuana have to do with movements and executive control functioning. In essence, being high can cause delayed movements and can diminish the efficacy of your decision making processes. When driving, this can have dire consequences, making it more difficult to avoid obstacles or react to situations quickly enough to avoid a collision.

Where do we stand in terms of assessments?

As of now, law enforcement across the country primarily employs roadside field sobriety tests, which are similar to those done for alcohol. If a driver fails this then further tests can be done, such as a drug-recognition expert conducting an advanced assessment as well as saliva, blood & urine tests. However, methods of assessing the presence or quantity of THC in an individual’s system at any particular moment have been challenged with respect to their accuracy. Some examples are as follows:

  • The government has approved the saliva test as a preliminary measurement of THC, but not all police forces are employing them. One of the issues with the saliva test is that it may not work as effectively in colder temperatures, making it potentially unreliable in Canada’s notoriously cold climate. They are also not 100% accurate. Saliva tests can also take up to 30 minutes to administer which render them less efficient than current roadside screenings of alcohol use. Saliva tests will only provide information on the presence of THC, not the drivers’ actual impairment, making its use limited. The roadside tests are only preliminary in nature; if a person fails one it can lead to an arrest for additional testing, the results of the saliva test are not admissible as evidence in isolation in a court of law.
  • Other tests will be done following a field and saliva test, but they likewise, have their own shortcomings. First, blood and urine tests are even more invasive than oral tests. They also take quite a bit longer and have to be conducted in a lab. The saliva test acts as the initial screening; subsequent blood and urine test results are what would be used as evidence in a court of law. THC content decreases substantially after a couple of hours of smoking, making blood tests unreliable after a certain point. On the flip side, THC can also remain in the body for an extended period of time without a person smoking recently or showing symptoms of being high. THC is sometimes stored in body fat and so tests can still detect it long after it’s relevant to assess someone’s impairment in a driving or work-related situation. For example, a regular marijuana smoker who quit 3 weeks ago, could test positive for THC in a urine test.
  • Another point to consider is that THC influences people in different ways. Some individuals with a high tolerance may not be impaired at 5 nanograms (ng), while someone without such tolerance would be “impaired” at a lower level of THC. If a field sobriety test is administered to both, a person with 1ng in their system could fail, while the other with 5ng could pass. But, according to the law, if an oral, blood or urine test were administered, the 1ng driver would not be charged while the 5ng would be. While it’s good to establish specific rules for cannabis use and driving, it’s also important to remember that individual differences can influence how impaired one becomes.

What is being done to address some of these issues?

  • A new cannabis breathalyser is being developed. Hound Labs have just made a device to detect THC in someone’s breath. It’s handheld, sensitive and only takes a few minutes, making it an enticing option for roadside assessments. Police forces have not yet adopted this, but with further testing it may come into mainstream use for law enforcement & employers.
  • THC can only be detected in someone’s breath based on how recently marijuana was smoked, and decreases as a function of time. This window of detection lasts only for about 2-3 hours, so if someone smoked 4 hours ago and was still impaired, it would not be able to register this. Additionally, it only detects recent marijuana use, meaning, it can detect use within the past few hours but is not able to distinguish between trace amounts and those that are deemed criminal offences.

While this may seem like a promising device, its effectiveness remains to be seen.

In summary, there is no clear consensus on any of the above noted issues – whether it be the legal limit, what level of THC is associated with impaired driving or how to deal with differing tolerances.

Reliance is still heavily placed on field sobriety tests, although new methods are always being developed and tested for widespread use. As it stands now, more research needs to be conducted to develop a better understanding of cannabis-related impairments and how to reliably conduct assessments.


The Centre for Addiction and Mental Health recommends waiting 6 hours after smoking before getting behind the wheel. https://www.camh.ca/-/media/files/pdfs—reports-and-books—research/canadas-lower-risk-guidelines-cannabis-pdf.pdf

For more information on cannabis-related impairment visit: https://www.canada.ca/en/services/policing/police/community-safety-policing/impaired-driving/drug-impaired-driving.html

For more information on the newly passed impaired-driving legislation visit: https://www.canada.ca/en/health-canada/news/2017/04/backgrounder_changestoimpaireddrivinglaws.html

This citation could be used for info on the saliva test (i.e. not as effective in cold climates & not 100% accurate – the original links are in this article as well).



For more information on Hound Labs newly-developed cannabis breathalyzer… https://houndlabs.com/product-overview/

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