Mandatory Alcohol Screening
Mandatory alcohol screening (MAS) is the power Canadian police have to demand a roadside breath sample from any lawfully stopped driver — without any reasonable suspicion that the driver has consumed alcohol. The power was created by Bill C-46 in 2018 as part of a major overhaul of impaired driving law. It is now codified in section 320.27(2) of the Criminal Code.
MAS does not eliminate the requirement that the stop itself be lawful. Random or pretextual stops without statutory authority remain unconstitutional. But once a driver has been validly stopped, MAS provides broad authority for screening.
How MAS changed the law
Before 2018, police needed reasonable suspicion of alcohol consumption — typically the smell of alcohol on the breath, slurred speech, glassy eyes, or an admission of drinking — before demanding an approved screening device sample. With MAS, that requirement was removed for any driver lawfully stopped under the Highway Traffic Act, the Criminal Code, or another statute. An officer with an ASD on hand can now demand a sample from anyone they have lawfully pulled over.
The consequences of refusal
Refusing or failing to comply with a MAS demand is itself a criminal offence under section 320.15. The penalties are the same as — and in some respects worse than — an over 80 conviction. First offence: minimum $2,000 fine and a 12-month driving prohibition. Second offence: minimum 30 days imprisonment. Third or subsequent offence: minimum 120 days imprisonment. Permanent criminal record on conviction.
Charter challenges
MAS has been the subject of ongoing Charter litigation. Courts have generally upheld the power as a justifiable limit on the section 8 right against unreasonable search and seizure, given the importance of impaired driving enforcement. But case-specific challenges remain available where: the underlying stop was not lawfully authorized; the screening device was not properly calibrated or maintained; the officer lacked a working ASD at the time of the demand; the demand was made in bad faith or for an improper purpose; or the screening was not conducted forthwith, as required.
Practical implications for drivers
For drivers, the practical effect of MAS is significant: there is no "safe" amount of alcohol to consume before driving in Ontario. Even a small amount can produce a fail or a warn-range reading on an ASD, leading either to a criminal investigation or to administrative penalties under the warn range rules.
How Mass Tsang challenges MAS-based charges
In every MAS-based file, the lawyers at Mass Tsang LLP review the legality of the stop, the conduct of the screening, and the timing and grounds for any further demands. To learn more about how police use roadside screening tools, see our blog post on how police use roadside screening tools in Ontario.
Related glossary terms
