Police across Canada will be testing three roadside devices on suspected drug-impaired drivers, despite the fact that none of the three devices can measure impairment.
It seems the RCMP are either ignorant of, or ignoring reality. Proving that someone has consumed cannabis does not determine if someone is driving while impaired. A recreational user may have a strong enough tolerance to not be impaired, and a medical marijuana user may actually need their medication to drive safely.
Courts in other jurisdictions have already found that testing for Cannabis consumption does not prove impairment. Arizona’s Supreme Court ruled that while state statute makes it illegal for a driver to be impaired by marijuana, the presence of a non-psychoactive compound does not constitute impairment under the law.
Justin Trudeau’s Liberal Party claims to support science, but if that claim is in any way true, they will drop this silly notion that measuring THC levels can determine a driver’s ability.
In 1983 a study by the US National Highway Transportation Safety Administration (NHTSA) tested drivers on simulators, and concluded that the only statistically significant effect associated with marijuana use was slower driving.
A NHTSA study in 1992 found that marijuana is rarely involved in driving accidents, except when combined with alcohol, concluding, “the THC-only drivers had an [accident] responsibility rate below that of the drug free drivers. While the difference was not statistically significant, there was no indication that cannabis by itself was a cause of fatal crashes.”
A separate NHTSA study from1993 tested Dutch drivers high on THC on real Dutch roads, concluding, “THC’s adverse effects on driving performance appear relatively small.”
In 1998 a study by the University of Adelaide and Transport South Australia analyzed blood samples from 2,500 accidents, and found that drivers with cannabis in their system were less likely to cause accidents than those without.
A University of Toronto study from 1999 found that cannabis users typically refrained from passing cars and drove at a more consistent speed than sober drivers.
A 2014 study concluded “Cannabis smoking history plays a major role in cannabinoid detection. These differences may impact clinical and impaired driving drug detection.”
In 2015 the National Highway Traffic Safety Administration released a study concluding that driving after smoking marijuana does not make you more likely to get into a car crash — especially when compared to driving after alcohol consumption.
Source links for all of these studies can be found within our previous articles: