What is Too High to Drive?

December 04, 2018, Kitchener, Ontario

Posted by: Robert Deutschmann, Personal Injury Lawyer

Since the legalization of recreational marijuana use last month, we’ve been hearing from the Ontario government that new testing methods are needed for officers doing road side sobriety testing. With the holiday season upon us the need will increase suddenly.

What we don’t know is how high is too high to drive. In jurisdictions where recreational marijuana use is legal such as Colorado, they report more than 20% of drivers in fatal accidents had cannabis in their systems. Whether that is relevant to the crashes or not we don’t know. We also don’t know what level of THC causes significant impairment.

A survey done in Colorado this year in found that almost 70% of people that use cannabis drove under the influence of it in the past year. 40% of those people didn’t think it had any impact on their driving ability. That is a problem. In Ontario nearly half of cannabis users report driving after using the drug.

Statistics Canada reports that there has been a steady increase in drug impaired driving rates in Canada over the period of 2008-2017 going from 2% to 10%. This is a significant increase and one that we have to examine. Are more people driving high, or are we catching more people driving high?

In Canada if an individual fails the road side sobriety test, or the roadside THC test they are taken to a police station where there is an almost one-hour long examination conducted after arrest. It is based on officer observation and the results of testing. The road side test detects THC in the saliva, but we have no measure of impairment. The drivers arrested will do subsequent sobriety tests and may be required to give a blood sample. Often the police can charge an individual for alcohol impaired driving as the driver has consumed more than one substance.

As of October 1, 2018 the number of Officers in Ontario trained as drug recognition experts is reported by the Toronto Star to be 240 (5 RCMP, 78 OPP, 157 municipal officers).  

We need more data on impairment and more enforcement capabilities if we hope to be able to combat drug impaired driving. The Ontario and federal  governments have launched  campaigns aimed at educating the public on drug impaired driving. The Federal one can be seen in full here:

Cannabis impairment

Impaired driving

Drug impaired driving has been a criminal offence since 1925.

Impaired driving is the leading cause of criminal death and injury in Canada.

Cannabis-impaired driving can result in injury or death for you, your passengers and others. Cannabis:

  • impairs your judgement
  • affects your ability to react
  • increases your chances of being in a crash

Never get into a car with an impaired driver. It is not worth the risk.

Mixing cannabis with alcohol increases your level of impairment and leads to an even greater risk of an accident. Footnote1

How long cannabis effects last

Impairment can last for more than 24 hours after cannabis use, well after other effects may have faded.

The time it takes for the effects of cannabis to wear off depends on:

  • how much and how often you have consumed it
  • whether it was smoked or ingested

There is no standard waiting time to drive after using cannabis. If you are using cannabis, do not drive. Find an alternative:

  • stay over
  • call a taxi
  • share a ride
  • use public transit
  • have a designated driver


Law enforcement officers are trained to detect drug-impaired driving. They enforce drug-impaired driving laws using:

  • Standard Field Sobriety Testing (SFST)
    • typically administered at the roadside
  • Drug Recognition Expert (DRE) evaluation
    • includes a series of tests and a toxicological sample (urine or blood)
  • Oral fluid drug screening equipment
    • Law enforcement can require a driver provide an oral fluid sample on approved oral fluid drug screening equipment
  • Blood samples
    • Law enforcement can demand a blood sample from a driver if they believe the driver has committed an offence

Law enforcement across Canada have SFST and DRE trained officers and the number of officers being trained is increasing. They also have training and access to approved oral fluid drug screening equipment.

Working together against impaired driving

We are working with provincial and territorial partners, as well as other groups such as:


You could face consequences like a fine, criminal charges or even jail time if you drive impaired by cannabis or other drugs. Learn more about how impaired driving laws are enforced in Canada.

Check out the Don't Drive High website on the dangers of drug-impaired driving. The site has a number of videos about the impacts of cannabis impairment.

The Ontario Government Fact sheet is here, and outlines the offences and penalties which range from the class of licence to the number of offences committed.


Posted under Accident Benefit News, drug impaired driving

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About Deutschmann Law

Deutschmann Law serves South-Western Ontario with offices in Kitchener-Waterloo, Cambridge, Woodstock, Brantford, Stratford and Ayr. The law practice of Robert Deutschmann focuses almost exclusively in personal injury and disability insurance matters. For more information, please visit or call us toll-free at 1-866-414-4878.

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