Since the legalization of recreational cannabis in states across the US and other countries, driving while high is regularly deemed unlawful and unsafe, but substantial improvements are needed to detect cannabis impairment in drivers, according to a new review study from the Canadian Medical Association Journal.
The study took a broader focus, looking at the associate between the legalization of recreational cannabis and fatal vehicle collisions in the US. It ultimately interprets recreational cannabis legalization in the US as associated with a relative increased risk of fatal vehicle collisions of 15 percent and a relative increase of associated deaths of 15 percent, with no conclusive difference between the first and subsequent years following legalization.
The study notes, with these findings, there could be a similar increase in fatal motor vehicle collisions, and associated deaths, in Canada following the recreational legalization of cannabis.
“We were really interested in trying to look and see if there was an association between legalization and increases in fatal motor vehicle collision,” said Sarah Windle, a lead author in the study. “The data weren’t there yet for Canada. So, we looked to the United States.”
Since more states have legalized adult-use cannabis, there has been a reported increase in Americans driving high. The analysis recognizes that cannabis impairment has more variables and improvements are needed to both ensure public safety and to protect the rights of legal cannabis users.
“We would love to have that one measure that says, ‘Okay, this person is impaired, or they aren’t,’” Windle said. “But unfortunately, in the case of cannabis, it just isn’t that simple.”
Researchers in the study confirmed the associated shifts in motor vehicle collisions and fatalities were small but significant, and used the data to determine 308 additional driving fatalities could occur each year, due to legalization of recreational cannabis in Canada.
“Whether this will actually play out in Canada is also another question,” Windle said. “There’s circumstances in Canada that are different from in the States which could prevent potential increases.”
This frame helped researchers open up the conversation to include measures and tools to track cannabis-impaired driving. Specifically, the detection measures in place for alcoholic inebriation written into law to detect impaired driving don’t necessarily correlate in a conducive way to cannabis use.
“We know that cannabis has an impact on driving,” Windle said. “Detecting cannabis, it doesn’t necessarily correspond directly to impairment. That’s a big, big challenge in this literature. At what level is somebody really impaired? And it seems that varies on many factors: by (the) individual, by their level of tolerance, how often are they using, what kind of cannabis, and its potency, are they using?”
Changes to the Criminal Code in 2018 sought to expand the laws and testing in regard to drug-impaired driving, and police can still use a field sobriety test or drug recognition expert evaluation to assess impairment, though researchers say the validity of those tests is still uncertain overall.
Technology is available to detect the presence of cannabis or other drugs in a person’s system, though professionals cite this as a more complicated issue, as the body’s level of THC does not always correlate well with impairment.
More research must be done, but in the meantime, people caught driving under the influence of cannabis over legally established limits can still be subject to fines and possible jail time. State legislation for cannabis-impaired driving varies in the U.S.
