The number of people Canadian police arrest annually for drug-impaired driving began increasing dramatically in 2018, hitting an all-time high (pardon the pun) in 2021, according to the latest incident-based crime data compiled by Statistics Canada. While police charged just under 2,000 motorists with the offence in 2017, this number more than doubled to hit 4,448 in 2021, and then settled into the low 3,000s range from 2022 to 2024. During this same period, the number of annual arrests for driving under the influence (DUI) of alcohol has been trending down , from 41,061 in 2017 to 27,429 in 2024.
The rise in drug-impaired driving arrests is undoubtedly connected to Canada’s legalization of cannabis in 2018, say the DUI criminal defence lawyers of the Greater Toronto Area’s Mass Tsang law firm. “We’ve seen a noticeable uptick in the number of clients seeking our legal skills to defend them against drug-impaired driving charges,” says Mass Tsang co-managing partner, Robbie Tsang . “And most of these clients were arrested for cannabis impaired driving.”
Robbie’s co-managing partner, Jeff Mass , adds, “What’s interesting about many of our DUI-cannabis clients is how little they know about drug-impaired driving laws. They tend to have vague notions that driving stoned is illegal, but don’t always realize that it carries similar penalties as an alcohol-related DUI. Additionally, some of these clients don’t believe that cannabis impairs driving skills to the same degree as alcohol.”
With these thoughts in mind, let’s examine the issue by reviewing the most frequently asked questions about cannabis impaired driving.
According to the Canadian Centre on Substance Use and Addiction (CCSUA), studies have identified numerous ways that cannabis can have a negative effect on cognitive and motor tasks necessary for safe driving. “The weight of evidence [from these studies] clearly reveals significant psychomotor impairment as a result of cannabis use.” Key study findings on the effects of cannabis on driving performance include:
Some of these studies determined that even combining a small amount of alcohol with cannabis use significantly increased the negative impacts on driving performance. They also determined that there is considerable variability in how cannabis affects individuals, making it “difficult to predict the extent to which a given amount of cannabis will have an impact on a particular individual.”
According to Section 320.28 of the Criminal Code, along with cannabis, the types of drugs covered by DUI law include:
National data from police-reported incidents, roadside surveys, and toxicological analyses indicate that cannabis is the most common drug found in injured and fatally injured drivers. According to a 2022 CCSUA report , the rates of cannabis found in fatally injured drivers have been increasing since legalization.
Driving while impaired by drugs is a Section 320.14 Criminal Code offence, with cannabis listed under Section 320.28 as a proscribed drug. If the Crown can prove beyond a reasonable doubt that your ability to operate a motor vehicle was impaired to any degree by a drug or a combination of alcohol and drugs, you can be convicted of the offence. Likewise, if the police investigation included blood testing that indicated blood drug concentrations equal to or exceeding concentrations prescribed by regulation.
The federal government has established three thresholds for cannabis blood concentrations in impaired driving cases. These thresholds and the prescribed penalties if convicted of a first-time cannabis DUI are:
Of course, the penalties don’t stop there, as driving while impaired by cannabis is also a provincial offence. In Ontario, a first-time criminal conviction for cannabis DUI also results in:
| THC Blood Level | Offence Type | Penalty for First Conviction |
|---|---|---|
| 2–5 ng/mL | Summary Conviction | Max $1,000 fine |
| 5+ ng/mL | Hybrid Offence | Min $1,000 fine, up to 2 years (summary) or 10 years (indictment) imprisonment |
| 2.5+ ng/mL THC + 50 mg alcohol/100 mL | Hybrid Offence | Same as above (treated as combined impairment offence) |
As of 2018, Canadian police have the legal authority to conduct roadside testing of any driver for alcohol or drug impairment. If an approved portable drug screening device is in their possession or within proximity by another officer, they can demand that you provide a saliva sample. Should the device register positive for cannabis concentrations (or other drugs), they can then require the driver to submit to blood sampling or undergo drug recognition evaluation (DRE) by a specially trained officer. While roadside testing results are not admissible as evidence in court, blood testing results and DRE officer testimony are. If you refuse to submit to roadside drug screening or subsequent testing, police can charge you with a Section 320.15 refusing to provide a sample DUI offence , which carries the same penalties upon conviction as a standard DUI.
Due to variabilities in how cannabis affects people, there is no one-size-fits-all answer to this question. From a road safety perspective, casual users should wait at least six to eight hours after toking before driving. Regular users, and those who’ve eaten edibles or smoked high-THC strains or multiple joints, should probably delay driving for at least eight to 12 hours.
From a safety from cannabis DUI charges perspective, oral and blood screening can detect THC concentrations for up to four to 12 hours after smoking or ingesting cannabis, with potency, amount consumed, and other factors dictating how long the THC might be detectable. Thus, if you’re wondering whether you can get a cannabis DUI the next morning after consuming cannabis the night before, the answer is a definite maybe.
If you’re facing cannabis impaired driving charges due to blood testing or a DRE officer’s assessment, consult with the experienced DUI criminal defence lawyers of Mass Tsang. With a 91% DUI case success rate, our legal team is highly adept at challenging blood drug testing, dismantling witness testimony, raising charter rights issues, and exposing other flaws in the Crown’s evidence and narrative. To schedule a free case evaluation of your cannabis DUI charges, contact us today.
