Impairment Vs Presence Of Cannabis: The International Cannabis Driving Debate Continues
Around the world, the debate continues about how to quantify the presence of cannabis in an individual’s system and how it relates to their ability to operate a vehicle.
Nobody in this debate believes that anyone unable to drive should get behind the wheel of a car. Instead, the issue lies in the difficulty of creating a one-size-fits-all rule for a very complicated issue: how to judge if someone is too impaired to operate a vehicle.
Various parties have proposed multiple metrics, including the presence of cannabis in saliva, the levels of cannabis in the blood, and actual impairment.
Cannabis And Driving Laws In The USA
For more than two decades, the U.S. has studied the effects of cannabis on driving and has a wealth of information to draw upon. However, despite the volume of studies, policymakers have not reached a consensus, which is not surprising given the biological nuances of cannabis (versus a substance like alcohol).
One of the main issues behind defining impairment is the quantification of cannabis in the system. When one smokes cannabis, the absorption and impairment vary widely depending on several factors.
Suggested Strategies To Address Cannabis Consumption And Driving In The U.S.
A suggestion to address the issue of cannabis consumption and driving is a three-level approach to quantifying impairment.
The first level is effect-based. Here, law enforcement officers look for proof that there is impairment and it is due to the consumption of a drug. Commonly accepted tests like the ability to walk in a straight line may demonstrate that a driver is impaired. An effect-based approach can help to offset the fact that different cannabis consumption methods produce the strongest effects at disparate times; smoking cannabis has its most potent effects for the first 20 to 30 minutes after smoking, while oral dosages may take effect after one hour of consumption.
If the effect-based method is unclear, law enforcement may measure the amount of THC in an individual’s system. However, unlike alcohol, THC can remain in the system for long periods and build up over hours, days and months, making it very difficult to establish a simple presence rule.
The third level of testing is a quantitative threshold. Many U.S. states have adopted a valuation system based on the presence of THC in the bloodstream, though that level varies considerably from state to state. In Ohio and Nevada, more than 0.2 ng/ml of blood is considered …