In September of this year, a car was stopped in Saanich for exceeding the speed limit in a school zone. The officer noted a strong odour of cannabis coming from the vehicle and confronted the driver and passengers who admitted that they had smoked a joint to celebrate dropping their children off for the first day back at school (Having kids of my own, I can sympathize with the feeling, but come on, people).
Rather than immediate arrest, a drug recognition expert was summoned, but failed to show that the driver was unfit to drive and off the moms went. This case serves to illustrate three key points regarding cannabis and driving.
- Cannabis produces a relatively low level of impairment
- Per se limits are arbitrary and not supported by science.
- Roadside breath/saliva/blood testing is of very limited utility
1.Impairment from cannabis
Many have raised concerns about the impact of recreational marijuana on road safety. These fears are likely exaggerated; research from epidemiological and simulator studies has lead us to understand that cannabis use presents a relatively low risk to drivers. Drivers who have consumed cannabis have a 30–40% increased risk of being in an accident, about the same as someone who has a BAC of 0.03–0.04. For comparisons sake, federal law criminalizes driving with a blood alcohol level of 0.08, which is associated with a 200% increase in accident risk. Simulator research shows that those who have consumed cannabis are aware of their impairment and tend to drive slower and leave more distance between them and the vehicle ahead.
In the real world, despite the proliferation of dispensaries in Vancouver and the rest of British Columbia, a review of BC Coroners data does not show a significant effect on the total number of fatalities in the province or the number of fatalities.
The biggest challenge to the narrative of increased roadway chaos comes from work done by Rees and Anderson. This study showed that in US states that had legalized medical marijuana, there was a consistent 9 % decrease in fatalities the year following legalization. The authors proposed a number of reasons for this, particularly that their research also showed decreased beer sales and binge drinking. Alcohol tends to be much more impairing than cannabis, so if there is a substitution effect, then traffic fatalities should decrease. Fatalities may also have decreased due to different social habits. Consuming alcohol in a bar or in other social settings and then driving or walking home contributes substantially to fatalities. Between the smell and stigma, most people tend to be discrete with their cannabis use, staying at home rather than travelling to and from a communal consumption site. This could change with social acceptance or the rise of vapor lounges.
2. Per se limits. (Per se = in itself, inherent)
Many US States prohibit driving with blood THC concentration of 2-5 ng/mL. Others go farther and have a zero tolerance policy, which the Solicitor General of British Columbia prefers. However, a recent AAA report on cannabis and driving pointed out that laws based on THC levels are arbitrary and useless.
Alcohol delivers a predictable level of impairment as blood alcohol level rises, so much so that we allow criminal penalties to be applied for driving with a BAC of 0.08, even if impairment has not been established. The difficulty is that we do not have the same information for other drugs. For cannabis, it has become clear that impairment is not easily related to blood THC levels. This becomes a particular problem as Canadian courts have already demonstrated that impairment is the issue, even if there has been known consumption of cannabis. Those using cannabis for medical reasons may always test positive and be therefore prohibited from driving, unfairly stigmatized compared to the users of alcohol, opiates, benzodiazepines,zopiclone or even Benadyl.
Driving stoned is more dangerous than driving sober, but the difference is more like the additional risk of driving while sleepy or angry than it is like the additional risk of driving drunk. It’s nowhere near as dangerous as driving while using a cellphone, even hands-free. Stoned driving should be a traffic offense, not a crime like drunk driving. Traffic risks aren’t a substantial objection to legalization, though of course smart policy would discourage driving stoned, and especially driving with both cannabis and alcohol on board. -Mark Kleiman, the architect of cannabis legalization in Washington State
3. Roadside testing
Roadside testing for cannabis is doomed to failure despite hopeful press releases. There is a tech rush to develop standardized THC breathalyzers, particularly one that can separate recent from past usage. The problem is that it doesn’t matter.On a practical level, any technology to be adopted would still have to undergo years of testing under varied environmental circumstances and legal challenges before being accepted. And ultimately the concern for the courts is not the type or amount of substance consumed, but whether impairment is present. That is why an assessment by a drug recognition expert remains the gold standard in court. However these experts are scarce, expensive and rely on very basic physical testing. The future of impairment testing is going to be devices that measure reaction time, eye movements and attention span; of course there’s an app for that.
This article was originally conceived as a refutation of drug simulation hardware such as marijuana goggles and the impaired driving suit that has been touring Canada. Each show is accompanied by an article where the reporter straps on weights, goggles with distracting lights and neck collars to simulate the experience of being high. The reporter then gets to climb into a car they have never been in and attempt to drive an obstacle course as a malfunctioning cyborg, mowing down several cones or whatever else is serving as a proxy for an innocent pedestrian. But it’s all rubbish. None of these have been tested to see if they accurately represent the conditions they are trying to simulate and it is clear that wearing one of these suits is far more impairing than using cannabis. This is nothing more than drug war theatre that only diminishes any organization’s credibility.
To retain credibility in fighting impaired driving, we have to focus on all causes. Canada still remains at the top of industrialized nations in terms of per capita road fatalities linked to alcohol. Numbers are improving, but as an emergency physician serving a rural area, I still see trauma victims with shocking blood alcohol levels. Distracted driving seems to have become a way of life, the soft blue glow emanating from between the legs of the nighttime driver creating a peril far greater than cannabis.
Driving stoned is more dangerous than driving sober, but the difference is more like the additional risk of driving while sleepy or angry than it is like the additional risk of driving drunk. It’s nowhere near as dangerous as driving while using a cellphone, even hands-free. Stoned driving should be a traffic offense, not a crime like drunk driving. Traffic risks aren’t a substantial objection to legalization, though of course smart policy would discourage driving stoned, and especially driving with both cannabis and alcohol on board.
This last point is probably the most important in how legalization of cannabis is going to affect traffic mortality. Alcohol in combination with any drug makes driving far more dangerous and co-consumption with cannabis should be discouraged. If recreational substitution of cannabis for alcohol takes place, overall fatalities could well drop.
Ian Mitchell is an Emergency Physician. Medical Volunteer at Burning Man and other Festivals. Find him on Twitter at @travels2little