RESEARCH - Impaired Driving & Legalization of Recreational Cannabis

A recent article in the Canadian Medical Association Journal examined impaired driving and the legalization of recreational cannabis. It concluded that there is potential for a small but important increase in fatal motor vehicle collisions due to recreational marihuana use. Extrapolating from US evidence suggests that this could add up to about 300 additional crash fatalities each year.

The article addresses the following topics:

  • What is known about the use of cannabis and driving in Canada?
  • How has legalization of recreational cannabis affected the incidence of motor vehicle collisions in other jurisdictions?
  • Are steps to detect and deter cannabis-impaired driving in Canada likely to be effective?
  • Can health care professionals help to prevent cannabis-impaired driving?

A PDF version of the article is available for download.

A study made by Dr. Russell Callaghan of the University of BC Northern titled "Canada’s cannabis legalization and drivers’ traffic-injury presentations to emergency departments in Ontario and Alberta, 2015-2019" found the following:

The project reviewed all Ontario and Alberta emergency department data from April 1, 2015 to Dec. 31, 2019. The team found that, immediately after cannabis legalization, there was no evidence of significant changes in traffic-injury emergency department visits among all drivers or youth drivers.
“Implementation of cannabis legalization has raised a common concern that such legislation might increase traffic-related harms, especially among youth,” says Dr. Callaghan. “Our results, however, show no evidence that legalization was associated with significant changes in emergency department traffic-injury presentations.”

This article is available through Sci-Hub.


Saw a study done in the 60's.

Saw a study done in the 60's. It was conducted using alcohol, marijuana and placebos.

What I remember was alcohol most recognised their driving ability was impaired where with marijuana although there was impairment many felt their reaction time improved.

Interestingly one person in the study their driving improved with two drinks or some marijuana. Very nervous driver and their jerky steering smoothed out.

In general even the minimum amount of intoxicants decreased ones driving ability. In my opinion the level should be 0. Why play with fate and all of us have different tolerance levels which do change with other factors.

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