Thanish Ahmed

According to research published in the Frontiers in Psychiatry (2021) and a report by NORML (2021), investigators from both Germany and the United States spent the last ten years examining research studies concerning THC levels and concluded, “The presence of THC concentrations in blood is an unreliable predictor of impaired driving performance.” 

“There is no clear overall relationship with THC blood or serum levels and driving skills or crash risk.

Not surprisingly, there is no unanimous agreement on potential THC legal cut-off levels. Therefore, the various THC concentrations used to define a cannabis-related driving offense in EU [European Union] countries and some US-states varying between 1 and up to 7 ng/ml alone may not be appropriate to evaluate driving skill impairment comprehensively.” 

These findings are consistent with numerous other studies that have been going on for over 20 years in some parts of the world. 

“A 2019 report issued by the Congressional Research Service stated: “Research studies have been unable to consistently correlate levels of marijuana consumption, or THC in a person’s body, and levels of impairment. Thus, some researchers, and the National Highway Traffic Safety Administration, have observed that using a measure of THC as evidence of a driver’s impairment is not supported by scientific evidence to date.” 

You might be wondering why these studies are important?

As more states attempt to enact legislation using THC levels as justification for punitive action against drivers testing positive for THC with low levels we need to be able to show that individuals process THC at different metabolic rates. These studies show using the amount of THC in someones system could lead down a dangerous road. Where we will see the continuation of people being unfairly targeted as cannabis consumers to the financial benefit of the justice system. 

“NORML has long opposed the imposition of THC thresholds for cannabinoids in traffic safety legislation.”

I’m thick, I could test positive for months with no use, and you never know how intensive these tests could get. I say, we stamp it out before they start the fire. I agree with Norml and encourage you to stay updated on cannabis related impairment laws in your region. Stay current on the research, and vote against low level positives for THC impairment laws.  


Analysis: THC Per Se Thresholds Are Unreliable Indicators of Psychomotor Impairment

Cannabis Use and Car Crashes: A Review

Front. Psychiatry, 28 May 2021