Calgary Police Service

Impaired driving

Impaired driving is when your ability to operate a motor vehicle is impaired by a substance, such as alcohol or drugs.

Penalties for a first offence are:

  • License suspension (Canada-wide) for an average of one year
  • $1,000 fine – fines increase with subsequent offences
  • Higher insurance costs
  • Cross-border implications

How do I report a driver that seems to be impaired?
Call 9-1-1. Do not attempt to follow the driver or place yourself in danger.

How much alcohol or cannabis can I consume and not be impaired?
The only safe level is zero. Alcohol and drugs, including cannabis, affect everyone differently. There are many factors that can increase the effects on an individual.

Research from the Canadian Centre of Substance Use and Addiction shows that, on average, cannabis use doubles the risk of being involved in a collision.

They found that driving skills are negatively affected after consuming cannabis, including the reduced ability to:

  • Track moving objects
  • Respond to more than one source of information
  • Respond to sudden changes in a driving environment

The risk of collision greatly increases if cannabis is consumed with alcohol. Mixing alcohol and drugs such as cannabis significantly increases impairment. In Alberta:

  • 24.1 per cent of all road fatalities involved a driver who tested positive for both alcohol and drugs in 2013.
  • 389 people were killed and 5,969 people were injured in alcohol-related collisions between 2013 and 2015.

How is it determined if someone is impaired by alcohol or drugs?
If an officer has a reasonable suspicion to believe a driver is impaired by a drug, the Criminal Code of Canada gives police the power to demand that person perform a physical sobriety test at the roadside, which would be conducted by a trained evaluating officer. If the evaluating officer determines the driver is impaired, then the driver can be arrested for impaired driving.

If the officer has formed the opinion that a person is impaired by a drug, then a drug recognition expert will be used to determine if the person is impaired and what drug category the person is impaired by.

Drug classification is established through an evaluation of the driver in accordance with the drug recognition expert program. This initially includes a standardized field sobriety test and if necessary, a full evaluation by a drug recognition expert.

The DRE test involves a 12-step evaluation which includes:

  • Measuring the driver’s blood pressure
  • Pupil size
  • Body temperature
  • Pulse
  • Eye’s reaction to light
  • Horizontal gaze nystamus (HGN) test
  • Vertical gaze nystamus (VGN) test
  • Divided attention tests

There are three outcomes expected of a completed evaluation:

  • The driver is determined to be impaired by a drug falling under one of the seven categories:
    • CNS depressants (eg. valium)
    • Inhalants (eg. glue, gasoline)
    • Dissociative anesthetics (eg. dextromethorphan, PCP)
    • Cannabis (eg. THC)
    • CNS stimulants (eg. cocaine, methamphetamine)
    • Hallucinogens (eg. LSD, psilocybin)
    • Narcotic analgesics (eg. oxycodone, morphine, fentanyl)
  • The driver is determined not to be impaired
  • The driver is determined to have a medical condition

If a DRE determines a driver is impaired, they will request a body-fluid sample. This can include urine or blood. Under Bill C-46, certified blood technicians can be used to obtain a blood sample which will be sent for analysis at the national lab.

Charges and provincial sanctions may be laid once the results of the body-fluid sample have been received and confirm the DRE evaluation.

What device do you use to establish how much alcohol or drugs someone has had?
The Calgary Police Service uses the Alco-Sensor FST as the approved screening device to detect the presence of alcohol and the Intox EC/IR II as the instrument that provides the amount of alcohol in the person’s body.

Can I be arrested for driving under the influence of a prescription drug?
Yes. If you are impaired by a prescription drug, you can be charged for driving while impaired. Some prescription drugs have warning labels specifically prohibiting the operation of a motor vehicle for those taking the drug, or if the drug is not being taken as prescribed, you could be legally impaired.

Do I have to give a breath sample?
If an officer reads a Criminal Code demand (screening device or evidential) to a person they are required to provide a breath sample.

What happens if I refuse to give a breath sample?
You can be charged under the Criminal Code for refusing to provide a breath sample which carries the same jeopardy as being charged with impaired driving.

I heard there are ways someone can give a false sample, like smoking, chewing gum, or putting a penny under the tongue. Do they work?
No. The instruments used for investigating impaired driving are designed to detect alcohol, nothing else. All persons providing breath samples will have their mouth checked for foreign objects prior to providing breath samples.

Can you receive an impaired on a bicycle?

Can I get an impaired in the morning?
Yes. Alcohol can only eliminate from your body at a certain rate. If you went to bed with a high blood alcohol concentration and didn’t wait for the alcohol to eliminate from your body, you run the chance of still being impaired, and if caught, being charged.

What is the offence committed if someone is driving under the influence of a drug?
Section 320.14(1)(A) of the Criminal Code covers the offence of impaired driving and includes if someone is impaired by a drug.

What is the penalty for impaired driving under the influence of a drug?
The penalties for driving under the influence of a drug are the same as for driving under the influence of alcohol.

Under Alberta laws effective December 1, 2020, Bill 21 implemented serious, immediate and escalating consequences for impaired drivers. For more information visit safe roads Alberta.

Under Bill C-46:

Blood concentration level Federal Criminal penalty *        
Blood concentration level: 2 nanograms (ng) per milliletre (ml)
but less than 5 ng/ml THC
Federal Criminal penalty *: Maximum $1,000 fine (summary conviction)
Blood concentration level: 5 ng/ml or more THC **
2.5 ng/ml or more THC combined
with 50 mg/100ml or more alcohol
Federal Criminal penalty *:

First offence: Minimum $1,000 fine

Second offence: Mandatory 30 days imprisonment

Third offence: Mandatory 120 days imprisonment

Blood concentration level:

* Penalties are more serious for drivers who have high levels of impairment or who injure or kill others while driving impaired, and those who are repeat offenders.

** This section also includes penalties for exceeding any blood drug concentration as established in federal regulations. THC is just the first. Limits for illegal drugs may follow. 

Information on other changes to federal impaired driving laws is available on the Government of Canada website.

What if I refuse to comply with the demand for the field sobriety test or the tests to be performed by a Drug Recognition Expert?
Under section 254(5) of the Criminal Code you would be charged with refusing to comply and charged criminally, and the consequences would be the same as failing to comply or refusal of a breath demand.


In an emergency always call 911

Non-emergency 403-266-1234