Roadside screening is part of a sequence. The legal authority for the stop and demand, the type of device or test, the timing, and what follows a result can matter to both the criminal investigation and provincial licence consequences.
Primary legislation and official process sources checked October 5, 2026. Criminal law and court procedure can change; verify the current source before relying on a provision or deadline.
Traffic stop and observations
An investigation can begin with a lawful vehicle stop, collision response, checkpoint or other police interaction.
- driving observations
- odour or symptoms
- collision investigation
Alcohol screening
The Criminal Code authorizes specified approved screening demands in defined circumstances, including mandatory alcohol screening powers.
- approved screening device
- demand requirements
- test result
Drug screening
Drug investigations can involve oral-fluid screening, standardized field sobriety testing, drug recognition evaluation or biological samples where statutory requirements are met.
- oral fluid device
- SFST
- drug recognition evaluation
Screening versus evidentiary tests
A roadside screen can be used to decide whether further investigative steps are authorized; later breath, blood or drug analysis can serve a different evidentiary function.
- roadside screen
- approved instrument
- blood sample
Charter and timing issues
The law can scrutinize the authority, timing and implementation of demands, including access-to-counsel issues at different stages.
- lawful demand
- delay
- right to counsel
Official and authoritative sources
- Justice Canada — Criminal Code
- Justice Canada — Canadian Charter of Rights and Freedoms
- Nova Scotia Legal Aid — Criminal Law Resources