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How do police test for cannabis-impairment?

Region: Ontario Answer # 2553

Across Canada, police have been trained to detect if a driver is under the influence of a drug. The new Cannabis Act allows police to use approved drug screening devices to detect the recent presence of several drugs, including THC, cocaine and methamphetamine.

Roadside testing

By law, if a police officer suspects a driver has drugs or alcohol, or a combination of both, in their system, after they have been pulled over they can demand an oral fluid sample and/or conduct a Standardized Field Sobriety Test (SFST). These roadside tests cannot be used as grounds to lay a charge or used as evidence in a criminal trial. Therefore, if a driver fails one of these two tests, the police officer will have grounds to demand further testing at the police station.

1.  Standardized Field Sobriety Test (SFST)

A Standardized Field Sobriety Test (SFST) allows police officers to examine the eyes of drivers, as well as to put drivers through a series of tests, including having them:

  • walk in a straight line,
  • stand and turn, or
  • stand on one leg.

2.  Oral fluid (saliva) sample testing

Reasonable suspicion: Police need to have a reasonable suspicion that a driver has drugs in his or her system in order to demand a driver take a roadside oral fluid screening test.

A reasonable grounds to suspect could include a driver:

  • erratically moving in and out of lanes,
  • following other vehicles at unsafe distances,
  • having red eyes, muscle tremors or unusual speech patterns, etc.

Three-hour limit for bodily substance sample:

Under section 320.27(1) of the Criminal Code, police officers are allowed to demand bodily fluid testing for anyone who has operated a motor vehicle within three hours of the test. This includes oral fluid (saliva) testing at the roadside.

Blood drug concentration over the legal limit within two-hours of driving:

The three-hour time-limit for obtaining a bodily substance sample is not to be confused with the offence of impaired driving, which includes anyone who “has, within two hours after ceasing to operate a motor vehicle, a blood-drug concentration that is equal to or exceeds the blood-drug concentration for the drug that is prescribed by regulation.”

The prohibited levels for cannabis are as follows:

  • Cannabis (THC): Between 2 nanograms (ng) and 5 ng of THC per ml of blood (less serious offence); and 5 ng of THC or more per ml of blood (more serious offence)
  • Combination of alcohol and cannabis: 50 mg or more of alcohol per 100 ml blood and 2.5 ng or more of THC per ml of blood.

Testing equipment: If police demand an oral fluid sample, they can test a driver’s saliva by using an Approved Drug Screening Equipment (ADSE). In Canada, an oral fluid screening device contains both an oral fluid collection kit and a reader. The test can detect the presence of certain drugs in oral fluids, including THC, the main impairing chemical in cannabis, and determine if an illegal amount of cannabis with THC has recently been consumed. To see the drug categories for drugs other than cannabis, refer to the Blood Drug Concentration Regulations.

Testing at the police station

If a driver provides a positive oral sample test, or fails a SFST, they may be arrested and taken to a police station for further tests. At the police station, police officers trained as drug recognition experts, can conduct a drug recognition evaluation (DRE) on drivers they believe are impaired by drugs other than, or in addition to, alcohol.

1.  Drug Recognition Evaluation (DRE)

A DRE is more thorough than a SFST. While it includes sobriety tests that are similar to the SFST’s, it also involves conducting clinical tests, such as checking blood pressure, body temperature, pulse rate, and measuring pupil size in different lighting conditions. There are actually 12 steps to the drug recognition evaluation. More information can be found from the RCMP.

If after conducting a DRE an officer believes a driver’s ability to operate a motor vehicle has been impaired by drugs, the driver may be charged under section 320.14 of the Criminal Code.

2. Breath sample — evidentiary breath test

The police will normally demand a breath sample if they believe a driver has consumed alcohol, or to rule out impairment by alcohol where drug impairment is suspected. Breath tests taken at the police station or medical facility can be used as evidence in a criminal trial, and are therefore often referred to as evidentiary breath tests.

3. Bodily fluid samples — for alcohol and/or drug impairment

The police can also demand bodily fluid samples to confirm or negate findings from both a breath sample and DRE.

(a)  Blood samples

Blood samples must be taken under the supervision of a trained medical technician. Blood samples will be able to show:

Blood-Alcohol Concentration (BAC). If the concentration is found to be over 80 mg of alcohol per 100 ml of blood, while the driver was in control of a vehicle, this is a criminal offence commonly referred to as ‘over 80’. In such cases, drivers are usually charged with one or more criminal driving offences.

Blood-Drug Concentration. If the concentration of a drug to blood is found to be over the legal limit (2 ng or more of THC per ml of blood), it may lead to a charge of drug-impaired driving. (Refer to the Blood Drug Concentration Regulations to view the limits for other drugs)

(b)  Urine and saliva samples

Urine and saliva samples can be used to confirm the findings of a DRE, which may lead to criminal driving charges being laid.

Related offences

Depending on the findings of the police, the test results, and the specific circumstances, a driver may be charged with one or more criminal driving offences. In addition to the criminal offence of impaired driving, refusing to comply with a request for a sample or the performance of a test, or failing a test can also result in being charged with one or more of the following:

For more information on drug impaired offences and penalties, view What criminal laws apply to driving while using cannabis?

To erase your criminal record for simple cannabis possession or any other criminal charges, call toll-free 1-888-808-3628 or learn more at Pardon Partners. It’s easier than you think.

For legal advice and assistance with a cannabis related matter, contact our preferred cannabis law expert, Harrison Jordan Law .


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