Cannabis Impaired Driving Law Canada

Cannabis-impaired driving and per se limits post-legalization By Michelle Johal


Drug-impaired driving has been a criminal offence for many decades. What is new are the offences relating to blood-drug concentration limits for cannabis and the cannabis/alcohol combination.

Part 1 of Bill C-46 introduced a number of amendments to the Criminal Code in response to the legalization of cannabis in Canada. Part 2 of Bill C-46 replaced all the old driving provisions of the Criminal Code with an entirely new scheme. As a result, sections 249-261 of the Criminal Code have been repealed.[1]

The new laws raise a number of interesting legal questions about driving offences and cannabis. Here are my answers to12of the most anticipated questions about the subject:

  1. Q: What are the new Criminal Code offences relating to cannabis and driving?

   A:  Section 320.14(1) created three new drug-related offences for drivers who have consumed drugs within two hours of driving. They include:

  •  Having a blood drug concentration (BDC) equal to or more than the prescribed legal limit within two hours of operating a conveyance (paragraph 320.14(1)(c));
  • Having a combined BAC and BDC equal to or more than the prescribed legal limit within two hours of operating a conveyance (paragraph 320.14(1)(d)); and
  • Having a BDC over a prescribed limit that is lower than the BDC set under paragraph 320.14(1)(c) within two hours of operating a conveyance (subsection 320.14(4));[2]
  1. Q: What are the prohibited cannabis/blood concentrations or per se limits?

   A: There are two prohibited levels for THC, the primary psychoactive component of cannabis.

It is a summary conviction offence to have between 2 nanograms (ng) and 5 ng of THC per ml of blood. It is a hybrid offence to have 5 ng of THC or more per ml of blood.[3]

  1. Q: What if you drive with a combination of alcohol and cannabis?

   A: The prohibited levels of alcohol and cannabis, when found in combination, is 50mg or more of alcohol per 100ml blood and 2.5 ng or more of THC per ml of blood.[4]

  1. Q: What are the penalties if convicted of a cannabis-related driving offence?

   A: The following chart illustrates the penalties for offences relating to cannabis and driving:[5]

Charge 1st offence 2nd offence 3rd offence
  • Drug-impaired driving
  • Having 5 ng or more of THC per ml of blood within two hours of driving


  • Having a BAC of 50mg per 100 ml of blood and 2.5 ng or more of THC per 1 ml of blood within 2 hours of driving
Mandatory minimum:

$1000 fine


10 years imprisonment

Mandatory minimum:

30 days imprisonment


10 years imprisonment

Mandatory minimum:

120 days imprisonment


10 years imprisonment


Refusal to comply with demand for a sample



$2000 fine



Mandatory minimum: 30 days imprisonment

Maximum: 10 years imprisonment



Mandatory minimum: 120 days imprisonment

Maximum: 10 years imprisonment

Drug-impaired driving-summary conviction

  • Having over 2 ng but less than 5 ng of THC per ml of blood within 2 hours of driving

$1000 fine (Discretionary driving prohibition can be imposed)

Impaired driving causing bodily harm
  • Summary conviction: Max 2 years less a day
  •  Indictment: Maximum 14 years imprisonment

Impaired driving causing death


Indictment: Maximum life imprisonment


  1. Q: What are the rules as they relate to young, novice and commercial drivers and the consumption of cannabis and driving?

   A: Drivers 21 years old and under or novice drivers of any age (with G1, G2, M1, or M2 licenses) must not have any presence of cannabis in their system. The same rule applies to commercial drivers of vehicles requiring an A-F class licence, vehicles requiring a commercial vehicle operator’s registration, and road building machines.[6]

  1. Q: Are you eligible for the Reduced Suspension with Interlock program if convicted of an offence relating to cannabis and driving?

   A: The Reduced Suspension with Ignition Interlock Conduct Review Program allows eligible drivers convicted of a first-time alcohol-impaired driving offence under the Criminal Code to reduce their licence suspension in return for meeting specific requirements, such as the mandatory installation of an approved ignition interlock device in their vehicle.

It is not available if the circumstances of the offence involve impairment by drugs or a combination of drugs and alcohol.[7]

  1. Q: How do the police currently conduct cannabis-related driving investigations? 

   A: Since 2008, law enforcement has been authorized to use Standardized Field Sobriety Tests (SFST) and Drug Recognition Evaluations (DRE) to conduct drug-related investigations.

The Criminal Code gives police the authority to either arrest for impaired operation by drug or to conduct Standard Field Sobriety Tests (SFST) to establish grounds for an arrest.[8]The SFST evaluation process is akin to the use of an approved screening device that screens for certain alcohol levels. An SFST includes three components like asking the operator to walk in a line and turn, stand on one foot or follow a pen with their eyes, for example.

The new laws, specifically Section 320.27 permits police to make a drug-screening demand as part of their investigation. If the driver fails the SFST evaluation or drug-screening test, the police officer can rely on this failure to form grounds that the driver’s ability to operate a motor vehicle is impaired by drug or that they are over the per se limits.

The driver is then taken before a Drug Recognition Expert (DRE) for further testing at the police station.

Section 320.28(2) provides that if a peace officer has “reasonable grounds to believe” a person has operated a conveyance and their ability was impaired to any degree by drug or combination of drug and alcohol then they may demand as soon as practicable that the person comply with either an evaluation by a DRE or provide samples of their blood. The blood sample taken pursuant to this section can be analyzed to determine the person’s blood drug concentration.

If upon the completion of a DRE evaluation, that officer has reasonable grounds to believe that the operator is impaired by drugs or a combination of alcohol and drugs then they may make a demand for oral fluid, urine, or a blood sample.[9]

  1. Q: Is there an approved oral fluid drug screener currently in use?

   A: As of June 2018, police can demand a sample of oral fluid (saliva) on approved drug screening equipment at the roadside. At the present time oral fluid drug screeners are being used by some law enforcement agencies but not for criminal investigations in Ontario.[10] The current oral fluid drug screening technology is not able to detect drug-blood concentration with the same precision as an approved screening device can detect alcohol-blood concentration.

  1. Q: Has there been an increase in cannabis-related driving arrests post-legalization?

   A: It was certainly anticipated that there would be a significant number of cannabis-related driving cases post-legalization. However, police departments across the board have not observed a significant increase in charges post-legalization.[11]

An informal survey of defence counsel who regularly practice in this area have not seen a spike in the number of cases post-legalization either. However, there may be another explanation for this, at least in the short term. Until very recently (April 1 to be exact), the only way to legally acquire marijuana was online at the Ontario Cannabis Store. Now that privately-run retail stores that legally dispense cannabis are up and running this may change. Moreover, while the new laws empower police to take blood directly, not all police departments are trained to do it yet.[12]The few impaired by cannabis cases I have observed post-legalization involve police relying on SFST and DRE and urine, not blood.

Common sense suggests that when police departments are actually trained to start seizing blood samples and an oral fluid screener is actually approved for use in the field (in the criminal context)there may be a spike in arrests for cannabis-impaired driving or driving in excess of the per se limits.

  1. Q: How long is it recommended to wait before driving after consuming cannabis?

   A: Common sense suggests that you should never operate a motor vehicle right after consuming cannabis. However, unlike with alcohol, it is not easy to calculate average elimination rates for cannabis. (It is estimated that your average healthy person eliminates about 15 ml of alcohol per hour.)

There is also the fact that cannabis can impair each person differently. Impairment levels can vary across individuals based on a range of factors including, (a) time since consumption (b) THC levels in the cannabis product consumed (c) delivery method (smoked vs. ingested), (d) personal use patterns, frequency of use and (e) individual metabolism of THC.[13]

To muddy the waters further some studies have suggested that some impairment effects can last days or weeks, especially for chronic cannabis consumers. For example, a review by Bondallazet al noted acute and long-term dose-dependent impairments of specific cognitive functions and psychomotor abilities, extending beyond a few weeks after the cessation of use.[14]

In light the uncertainty in this area, there is no one-size-fits-all recommendation about how long you should wait to drive after consuming cannabis.

  1. Q: Why are the per se drug limits lower when they are combined with alcohol?

   A: Some studies have observed that the use of both alcohol and cannabis has been shown to lead to greater odds of making an error while driving than use of either alcohol or cannabis alone.[15]

  1. Q: Are constitutional challenges to the per se marijuana limits being contemplated at this time?

   A: Yes. The crux of the argument is this:  THC may remain in the body for several days or even weeks after the drug is used. This means it is theoretically possible for someone to fail the test even if they have not consumed cannabis recently AND without actually being impaired at the time of driving. The valid concern is if you consume cannabis on a Friday night, you should not be worried that you will be deemed unfit to drive to work on Monday morning.

Moreover, as it relates to the current per se limits some studies have observed that the correlation between blood levels and psychoactive effects of THC is challenged by a non-linear time relationship. This makes the detection of driving while impaired and the interpretation of single blood THC levels difficult.[16]



Bill C-46 has made the most significant changes to Canada’s impaired by drug driving laws that we have seen in over three decades. However, we are still in the very early months of the new Criminal Code provisions. What provisions will be upheld as constitutional and what will be struck down remains to be seen. Stay tuned.

For more information about Bill C-46 and the news laws that relate to cannabis and driving, I recommend the only text currently available on the subject: Impaired Driving and Other Criminal Code Driving Offences, Emond Publishing. November 2018. Authors: Karen Jokinen, Peter Keen.


[1]Bill C-46, An Act to amend the Criminal Code (offences relating to conveyances) and to make consequential amendments to other Acts, 1stSess, 42nd Leg. Canada, 2018.

[2]Section 320.14. See

[3] SOR 2018-148; Regulations Amending the Blood Drug Concentration Regulations, SOR 2018-149


[5] Penalties for drug-impaired driving, (Chart) https//

[6]Highway Traffic Act, 1991, R.S.O. 1991, C. H8


[8] Section 320.27(1)(a) provides police with the authority to demand an SFST to determine the presence of drugs in a person’s body.

[9] Section 320.28(4)(a)(b)

[10] Barrie police now have roadside testing device for cannabis,

[11] Mounties seeing smaller number of blood samples than expected under drug-impaired driving law, by Catharine Tunney, CBC news, posted: March 24th, 2019 [Internet] Available from


[13] Canadian Society of Forensic Sciences Drugs and Driving Committee. Report on Drug Screening Equipment – Oral Fluid [Internet]. Ottawa: ON: Available from

[14]Bondallaz et al, Ibid.

[15]Bondallaz et al, Cannabis and its effects on driving skills. Forensic Science International 268. 92-102.

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