Canada’s impaired driving laws were rewritten from the ground up under federal legislation known as Bill C-46, with the core alcohol reforms coming into force on December 18, 2018. Those changes replaced the old Criminal Code framework with a consolidated set of rules found in Part VIII.1 of the Code. The three biggest shifts drivers need to understand are mandatory alcohol screening (police can demand a roadside breath test without suspecting you have been drinking), a new “within two hours” offence structure, and tougher penalties across the board. This guide breaks down what changed, why, and how federal law works alongside the rules in your province or territory.
One note before we start: this is a plain-language overview of federal law, not legal advice. Penalties and procedures depend on the facts of a case, and provinces layer their own administrative rules on top. For anything specific to your situation, speak with a lawyer or your provincial licensing authority.
What changed in Canada’s impaired driving laws?
Before December 2018, Canada’s drinking-and-driving provisions had been patched together over decades and were widely criticised as slow, complicated, and easy to challenge in court. The federal government repealed that framework and enacted a single, consolidated regime. In plain terms, the reform did four main things:
- Introduced mandatory alcohol screening (MAS), letting police demand a breath sample from any lawfully stopped driver without needing a reasonable suspicion of alcohol.
- Redefined the “over 80” offence as being at or over the limit within two hours of driving, which closed a long-standing legal loophole.
- Raised minimum fines and maximum penalties.
- Created measurable drug-impaired driving offences, including limits for cannabis (THC).
These are federal criminal changes that apply everywhere in the country. On top of them, each province and territory runs its own administrative penalties, roadside licence suspensions, and ignition interlock programs.
Bill C-46: the December 2018 overhaul
Bill C-46 was the vehicle for the reform. The alcohol-related provisions took effect on December 18, 2018, when the previous transportation offences were repealed and replaced by Part VIII.1 of the Criminal Code. The same modernisation created new drug-impaired driving offences, which arrived in the same period that cannabis was legalised for recreational use in Canada.
The government’s stated goals were to simplify the law, strengthen deterrence, and reduce the volume of drawn-out court challenges. Justice Canada has described impaired driving as the leading criminal cause of death and injury in Canada, which was the central justification for a tougher, clearer regime.
Mandatory alcohol screening (MAS)
Mandatory alcohol screening is the single most talked-about change. Under the old rules, an officer could only demand a roadside breath sample on an approved screening device if they had a reasonable suspicion that the driver had alcohol in their body. That often meant noticing slurred speech, the smell of alcohol, or an admission of drinking before testing.
Under MAS, an officer who has lawfully stopped a driver and has an approved screening device on hand can demand a breath sample without any such suspicion. Refusing to provide one is itself a criminal offence. Similar screening regimes are used in a number of other countries and were part of the case Parliament considered when it adopted the change.
The “within two hours” rule
One of the most technical but important changes was to when the offence is committed. Previously, the Crown had to prove a driver’s blood alcohol concentration (BAC) was over the limit at the time of driving. That opened the door to defences built around the timing of drinks, including the so-called bolus-drinking defence (claiming alcohol was consumed just before driving and had not yet been absorbed) and the intervening-drink defence (claiming alcohol was consumed after driving but before the test).
The new law makes it an offence to be at or over the limit within two hours of driving. That change largely eliminated those timing defences. A narrow exception remains for people who drank after driving with no reason to expect they would be tested, where the evidence is consistent with a legal BAC while actually driving.
The “at or over 80” BAC framework
The legal blood alcohol limit itself did not change: it remains 80 milligrams of alcohol per 100 millilitres of blood, commonly called 0.08. What changed was the wording. The offence shifted from being “over 80” to being at or over 80, which closed a gap where a reading of exactly 80 could previously be argued down.
Remember that 80 is the criminal threshold. Most provinces also enforce lower administrative “warn” thresholds that can trigger short roadside suspensions even when no criminal charge is laid, and new and young drivers face zero-tolerance rules in much of the country. Your province’s rules matter as much as the Criminal Code here.
Tougher penalties
Bill C-46 raised both the mandatory minimum fines for first offences and the maximum penalties available to the courts. A few features of the current framework stand out:
- Minimum fines for a first offence scale with how high the driver’s BAC was, and refusing to provide a sample carries the same minimum as the highest BAC band.
- Repeat offences carry mandatory jail time.
- Maximum sentences increased substantially, including up to life imprisonment for impaired driving causing death.
The exact figures are set out in the Criminal Code and summarised on the Department of Justice’s website; because sentencing also depends on the circumstances of the case and how the Crown proceeds, treat any single number you see quoted online with caution and check the current law.
Drug-impaired driving limits
The overhaul also created measurable limits for drug-impaired driving, which matters given cannabis legalisation. The offences are built around blood-drug concentration levels rather than a purely subjective judgment of impairment, with separate thresholds for lower-level and more serious offences and a combined alcohol-plus-THC offence. Certain other impairing drugs are subject to an “any detectable amount” standard.
Unlike alcohol screening, roadside drug screening still requires an officer to have a reasonable suspicion before demanding an oral fluid sample or a drug recognition evaluation. The specific thresholds are published by the Department of Justice.
How provinces layer their own penalties and interlock programs
The Criminal Code sets the national floor, but you experience impaired driving enforcement largely through provincial rules. Every province and territory administers its own scheme of roadside licence suspensions, vehicle impoundment, reinstatement steps, remedial education, and ignition interlock requirements. These administrative consequences are separate from any criminal charge and often take effect at the roadside, on the spot. Provinces also continue to tighten their rules independently of the federal reforms, so the details where you live can change from year to year.
One thing is consistent nationwide: an ignition interlock program is now a standard part of getting back on the road after an impaired driving offence. An interlock is a small in-car breath-testing device that prevents the vehicle from starting if it detects alcohol on the driver’s breath, and it asks for rolling re-tests while you drive. Many provinces let eligible drivers get back on the road sooner by enrolling in an approved interlock program.
What this means for drivers
The practical takeaway is simple: enforcement is broader, the old loopholes are mostly gone, and the consequences are more serious. Any lawful traffic stop can now include a breath test, being at or over the limit within two hours of driving is enough to be charged, and even a first offence carries a mandatory fine, a criminal record, and a licence suspension.
If you or someone you know is dealing with the aftermath of an impaired driving charge, understanding the interlock requirement early can make reinstatement faster and less stressful. Smart Start Canada provides ignition interlock services across the country. You can learn how the ignition interlock device works, review the probationary and voluntary program options, or find a service centre near you to get started.
Frequently asked questions
What are the new impaired driving laws in Canada?
They are the reforms enacted through Bill C-46, which overhauled the Criminal Code’s transportation offences. The main features are mandatory alcohol screening, a “within two hours” offence structure, higher minimum and maximum penalties, and defined limits for drug-impaired driving.
When did the new impaired driving laws come into effect?
The core alcohol reforms, including mandatory alcohol screening, came into force on December 18, 2018. The new drug-impaired driving offences were introduced in the same overall reform period, alongside cannabis legalisation.
Can police demand a breath sample without suspecting I’ve been drinking?
Yes. Under mandatory alcohol screening, an officer who has lawfully stopped you and has an approved screening device on hand can demand a breath sample without a reasonable suspicion that you have alcohol in your body. Refusing is a criminal offence.
What is the legal blood alcohol limit in Canada?
The criminal limit remains 80 milligrams of alcohol per 100 millilitres of blood (0.08). The reform reworded the offence so that being equal to or over 80 is captured. Most provinces also enforce lower administrative thresholds that can trigger roadside suspensions, and zero-tolerance rules often apply to new and young drivers.
What is the two-hour rule?
It makes it an offence to be at or over the limit within two hours of driving, rather than only at the moment of driving. This closed timing-based defences, such as claiming alcohol was consumed so recently that it had not yet raised your BAC while driving.
What are the penalties for a first impaired driving offence?
A first offence carries a mandatory minimum fine that scales with your BAC, along with a criminal record and a driving prohibition. Higher readings, refusals, repeat offences, and cases involving injury or death carry heavier penalties, up to and including imprisonment. The current figures are set out in the Criminal Code; check the Department of Justice’s summary for details.
Are there legal limits for cannabis and driving?
Yes. The reform created offences based on blood-drug concentration, with separate thresholds for lower-level and more serious offences and a combined alcohol-plus-THC offence. The specific limits are published by the Department of Justice.
Do impaired driving penalties differ by province?
Yes. The Criminal Code sets national criminal penalties, but each province and territory adds its own administrative rules, including roadside licence suspensions, vehicle impoundment, reinstatement fees, and ignition interlock programs. Check your provincial licensing authority for the current details where you live.
Is an ignition interlock required after an impaired driving conviction?
In most cases, yes. An ignition interlock program is a standard condition for reinstating driving privileges after an impaired driving offence, and many provinces let eligible drivers shorten their time off the road by enrolling in an approved program sooner.
Getting back on the road
Understanding the law is step one; the fastest practical step back to legal driving is usually your province’s interlock program. Smart Start Canada operates service centres across the country, with straightforward pricing published for each provincial program. Learn how the ignition interlock device works, explore probationary and voluntary options, or find your nearest service centre to book an installation.
Sources: Department of Justice Canada, Impaired Driving Laws and the Criminal Code of Canada.
Disclaimer: This article is provided by Smart Start Canada for general informational purposes only and is not legal advice. Impaired driving laws, penalties, and program requirements vary by province and territory and by individual circumstances, and they change over time. Nothing here should be relied on as a statement of the law in your jurisdiction. Always confirm current requirements with your provincial or territorial licensing authority, the court handling your case, or a licensed lawyer before making decisions. Program details, pricing, and availability are subject to change and may vary by location.