Research shows drivers perform poorly after consuming little amounts of marijuana

Published: October 23, 2018



Lawmakers around the world have often attempted to decide what is the cut off limit for impaired driving. That is the amount a driver is allowed to consume and still legally operate their vehicle. Much debate still surrounds this subject and legal marijuana has added further complications.

Traditionally, authorities have had to only consider legal limits for alcohol, but marijuana is now a factor following this month’s legalization of recreational pot in Canada. So, how much cannabis can a person consume and still drive. A study from the Research Institute of the McGill University Health Centre suggests drivers should perhaps consume nothing before getting behind the wheel.

Funded by the Canadian Automobile Association (CAA), the study found people who smoked just a small part of a joint were risker drivers compared to when they are sober. The research included participants who smoke cannabis occasionally and were asked to perform practical tests in a driving simulator.

One of the tests involved gauging driver ability to stop when a light turns red or to stay in lane. Drivers who had smoke marijuana within five hours of the test had poorer results:

“When the task was more complex and something more novel, that’s when they made more errors” said Isabelle Gélinas, who co-authored the study, in an interview with Canadian Underwriter. Researchers also looked at driver performance when they were sober, as well as at intervals of one, three, and five hours after consuming pot.

No Education

Marijuana for recreational use has only been legal in Canada for under a week. CAA representatives say there “hasn’t been a lot of overt public education” on cannabis and driving. Ian Jack, CAA’s managing director for communications and government relations, ADDS “It’s simply been, ‘don’t do it, it’s illegal,’”

“CAA wanted to address that myth that people are as good at driving stoned as they are sober. We are always interested in bringing information to the table rather than finger wagging.”

“We do not claim this study is the definitive last word on this subject. It’s an important start to the conversation on the science of cannabis and driving,” Jack said in an interview.