Driving Under the Influence: Cannabis Edition

Fluidextract cannabis indicaAs cannabis (marijuana) prohibition continues to die out, a growing number of countries around the world have declared cannabis as decriminalized, allowed it to be prescribed medically, or ceased enforcing laws against cannabis entirely. Next spring (July 1, 2018) Canada’s federal government will be joining Uruguay as the only other country on the planet to fully legalize cannabis.

Comprised of approximately 34 million registered motor vehicles and drivers on the road as young as 14 years old, Canada must now act to address the enigma and the potential public health hazard regarding driving under the influence of cannabis.

As research continues to display the potential benefits and concerns the plant may present, law enforcement agencies are now faced with implementing more accurate tests for “high driving.”

Pioneers of cannabis liberty like Colorado have placed laws prohibiting “high driving” that are modeled after the current alcohol model, which establishes a number system based on bodily samples (urine/blood/breath) to distinguish if a person is too intoxicated to drive.

The most common and notorious measure of driving under the influence (DUI) for alcohol is the breathalyzer; this device measures estimated blood alcohol content (BAC).  A BAC reading of 0.08% or higher is a legal marker for alcohol intoxication that suggests you are unfit to be driving a motor vehicle.

After decades of research and debate the unanimous conclusion that a BAC of 0.08% or above impairs the driver to an unsafe level was universally accepted.  This lead to the regulation of drunk driving we see today and this reading can/will be used as part of criminal prosecution.


This principle has inspired cannabis laws that correspondingly qualify a driver for a cannabis DUI if the driver is found to have 5 nanograms of THC per milliliter in their blood.  While this numeric method may appear sensible, the distinct physiological characteristics of alcohol and cannabis must be considered. Cannabis can be detected in body fluids for weeks after consumption, long after the effects have worn off.  Currently there are studies analyzing methods to determine safe levels of cannabis intoxication including breath tests, saliva tests, blood markers, as well as behavioral tests; however, we have yet to establish a universal primary option to use.

Driving Under the Influence

While any amount of cannabis consumption may place you at risk of driving impaired, the data to support the increased dangers of driving after consuming cannabis remain quite mixed.  Current research suggests that people who drive immediately after cannabis use (smoking) double their risk of getting into an accident and that the effects of THC on driving are strongest during the first hour. The College of Family Physicians of Canada provides the following guidelines to avoid driving under the influence of cannabis:

  1. Wait at least four hours after inhalation.
  2. Wait at least six hours after oral ingestion.
  3. Wait at least eight hours after inhalation or oral ingestion if you experience euphoria.

Adversely, some research poses a strong argument for cannabis as a performance enhancer, potentially allowing some people to more safely participate in driving tasks after cannabis consumption.  Growing evidence continues to display the dose-response relationship when it comes to cannabis intoxication.  The variables are many in number which makes developing an objective measure of cannabis intoxication troublesome.  Respected cannabis maven Leafly now acknowledges nearly 800 different strains of cannabis all possessing different chemical qualities and mental/physical health potential.

Alcohol over the limit

When cannabis is grown, based on careful calculation and planning, one of three types of cannabis will be created; Sativa, Indica, or hybrid.  Essentially, Indica strains offer a sedating/relaxing effect while sativa strains offer refreshing cerebral effects generally best utilized before participating in physical activity, social settings, or creative/art ventures. Hybrids can inherit potential effects from both sativa and indica plants allowing growers to target each strains desirable characteristics.  This puts forth a plethora of different outcomes when it comes to individual consumption.

Green cross

Nonetheless, driving under the influence of cannabis poses similar risks as drunk driving but is not as easy to delineate. Lacking the innovation to set a limit, measure objectively, and abide by set laws, law enforcement is currently commonly forced to make a subjective decision based on observed impairment.  Continued research and education is needed to improve the safe and therapeutic consumption of cannabis; in the meantime, be cautious, use your best judgement and abide by the laws in place to avoid harming yourself and others.  Lastly, persist in staying updated and informed on the shifting cannabis landscape as the cannabis revolution continues to unfold.



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