Regular Cannabis Users Drive As Safely As Sober People, New Study Suggests

September 1, 2021 – by Chris Moore

Researchers found that weed impaired driving performance in occasional pot users, but daily stoners were able to drive as safely as sober drivers.

Regular cannabis users are able to drive as safely as sober people, even while stoned, according to a new study published in the Accident Analysis and Prevention journal.

To investigate the potential risks of cannabis-impaired driving, a team of researchers affiliated with the University of Colorado recruited 85 adults between the ages of 25 and 45 to participate in a simulated driving study. The subject pool included 31 subjects who reported using cannabis every day, 24 who said they got high one to two times a week, and 30 people who did not use cannabis at all.

Each subject performed two separate tests using a car-based driving simulator with a 45 minute break in between each session. During the break, each cannabis-using subject was given 15 minutes to get as high as they wanted using flower that they purchased themselves. Researchers asked participants to bring bud with 15 to 30 percent THC content, but did not impose any other limitations on what kind of weed could be used. The control group of non-users remained sober for both of the driving tests.

Using the MiniSim™ National Advanced Driving Simulator, researchers obtained two separate measures of driving performance in simulated urban driving scenarios. The simulator recorded data on the standard deviation of lateral placement (SDLP), which measures a driver’s ability to safely remain in their lane on straight road segments and turns. Researchers also kept track of whether drivers drove faster or slower than the speed limits posted in the simulation.

Researchers found that the occasional pot users performed significantly worse on the SDLP test after getting high, which suggests that weed could indeed be interfering with their ability to drive safely. But experienced, daily users were able to drive as safely as the sober control group. Occasional users also drove slightly faster than the posted speed limit when they were stoned, but not fast enough to be statistically significant. On the other hand, daily pot users drove significantly slower than the speed limit after getting high.

“We observed a decrement in driving performance assessed by SDLP after acute cannabis smoking that was statistically significant only in the occasional users in comparison to the nonusers,” the study authors concluded. “Daily users drove slower after cannabis use as compared to the occasional use group and non-users.”

This study brings new insight to a growing field of research on cannabis-impaired driving. Anti-legalization groups and law enforcement officials have constantly warned that adult-use legalization will lead to an increase in pot-related traffic accidents, but the data so far suggests that this is not the case. Several recent research studies have found that it is more dangerous to drive under the influence of prescription pills than weed, and that THC alone does not increase the risk of accidents.

This research also clearly highlights the fact that THC blood tests cannot effectively predict whether or not a driver is too stoned to drive safely. Many US states and Canadian provinces have imposed per se THC limits for drivers, and anyone caught exceeding that limit can be fined or even have their license suspended.

The present study reports that the daily cannabis users had six times as much THC in their blood as occasional users – but in this case, the users with higher THC blood levels were actually driving more safely than those with lower levels. Researchers have also found that past-day weed smoking can cause a person to test over the limit for THC, even though they are completely sober at the time of the test.

Story from

Cannabis and driving study casts doubt on zero-tolerance limits for THC

People using a driving simulator showed no signs of impairment a day after they smoked cannabis, though they still tested positive for THC, its main psychoactive component, a recently-published paper says.

The research has implications for laws and workplace rules that require no trace of THC, which Scott Macdonald, a retired professor at the University of Victoria, calls “not scientific.”

“I consider it one of the biggest myths about cannabis, that there are 24-hour hangover effects that are measurable,” he said.  “When people smoke cannabis, they’re only impaired for a short, short period of time. You could have THC in your bloodstream, but you’re not a danger.”

Researchers at the Toronto-based Centre for Addiction and Mental Health gave participants 10 minutes to smoke cannabis to a level they chose, then tested them in a driving simulator.

Because they were allowed to control their own consumption, THC blood levels in the group varied. They ranged from zero to 42 nanograms per millilitre, which would be nearly 10 times the legal limit to drive.

READ MORE: How long does cannabis stay in your system?

The driving simulator’s scenario involved a nine-kilometre drive on a stretch of rural highway signed at 80 km/h, with a few simple problems to solve, such as a slow-moving vehicle.

Immediately after smoking, the THC group showed signs of impairment, centring the imaginary car poorly in its lane and driving inappropriately slowly.

But in further tests 24 and 48 hours later, they still had detectable levels of THC, but performed normally in the driving simulator.

“We found significant evidence of difference in driver behaviour, heart rate and self-reported drug effects 30 minutes after smoking cannabis, but … we found little evidence to support residual effects,” the authors wrote.

The study shows that similarly to alcohol, cannabis impairment disappears within a day of consumption at most, if not much earlier.

However, THC can keep showing up on tests long after any impairment has ended — unlike alcohol, which would stop being detectable as impairment went away.

“The biological tests are not useful for identifying people that represent a safety risk,” Macdonald says. “What we’re left with is behavioural symptoms. We’re still working on developing tests to assess whether an individual who consumes cannabis is a safety risk. It’s hard to do.

“Cannabis is not in the same class as alcohol, in terms of safety risk. Alcohol is much, much worse.”

Several provinces forbid young or new drivers from having any detectable levels of THC.

In Ontario, for example, drivers violating a zero-tolerance rule for THC face a three-day licence suspension, $250 fine and $281 licence reinstatement fee for the first offence. Penalties increase for repeat offenders.

Saskatchewan took what may be Canada’s strictest approach: new drivers in the province with any level at all of THC face a 60-day licence suspension, a three-day vehicle seizure and four demerit points.

Ontario’s transport ministry defends the policy.

Several provinces forbid young or new drivers from having any detectable levels of THC.

In Ontario, for example, drivers violating a zero-tolerance rule for THC face a three-day licence suspension, $250 fine and $281 licence reinstatement fee for the first offence. Penalties increase for repeat offenders.

Saskatchewan took what may be Canada’s strictest approach: new drivers in the province with any level at all of THC face a 60-day licence suspension, a three-day vehicle seizure and four demerit points.

Ontario’s transport ministry defends the policy.

“I think [28-day bans] are excessive and not scientifically based, especially now that cannabis is legal,” Macdonald says. “If cannabis was illegal, I could see it from that perspective. It’s not scientifically based in terms of them being a risk for the public if they’ve used cannabis in the last 28 days.”

Toronto police are open to revisiting the 28-day ban, spokesperson Const. Victor Kwong wrote in an e-mail.

“(The rule) was made thoughtfully and based on sound advice and evidence, considering the critical role members play in ensuring a safe workplace and a safe community. We will continue to research and explore this procedure. If at any time there is new science or research to cause us to re-evaluate our processes, we will do so.”

A B.C. labour arbitrator recently ruled against TransLink, the Vancouver-area transit authority, over its handling of an employee’s positive test for THC.

David Solomon, a train attendant, was forced to undergo drug tests twice a month for a year, despite a doctor’s opinion that his cannabis use wasn’t a problem. Solomon had to call the testing service daily to find out whether he was going to have a test that day or not, and go to a lab to be tested if the answer was yes.

READ MORE: TransLink ordered to stop drug testing pot-smoking SkyTrain attendant

The military allows cannabis use at some times for some members, depending on their jobs. Some, like divers, aircrew, members of submarine crews and drone operators, have a 28-day prohibition similar to the more restrictive police forces.

“Many jobs — typically those which are safety sensitive — have adopted a zero tolerance policy, but as cannabis becomes more integrated into society, we’re going to need to consider policies that are reflective of this change and embrace a better understanding of cannabis and its effects,” Valleriani wrote.

“Some jobs require drug and alcohol tests as a condition of employment, but it begs the question of how workplaces can manage the risk of impairment without an accurate measure of it.”

The study was published this week in the Journal of Drug and Alcohol Dependence. Macdonald was not involved with it.

During the study, a placebo group was given joints with no THC to smoke, but it turned out that participants were well aware of whether they had consumed THC or not, with over 90 per cent in both groups accurately saying what group they were in.

When they were asked whether they would be comfortable driving a real car, 80 per cent of the placebo group said they would, as opposed to under 30 per cent in the THC group.

“It has the biggest sample size of any sample that I know of,” Macdonald said of the study’s 91 participants.

CAMH and Health Canada, where the study’s lead author works, did not make anybody available for an interview.

Story From Global News

What police are getting wrong about pot-impaired driving

Marijuana Users Are Safer Drivers Than Non-Marijuana Users, New Study Shows

A new study released by United States auto insurance quote provider shows that statistically speaking, marijuana users are safer drivers than non-marijuana users.

In a recent study,, a national quote provider for online car insurance quotes, cites a strong correlation between traffic-related accidents and marijuana use. The study, which looks at statistics regarding accidents, traffic violations, and insurance prices, seeks to dispel the thought that “driving while stoned” is dangerous.

In the study, points out that the only significant effect that marijuana has on operating a motor vehicle is slower driving. says, while referencing a study by the US National Highway Transportation Safety Administration (NHTSA), that driving slower “is arguably a positive thing” and that driving under the influence of marijuana “might even make you a safer driver.” A similar study by the NHTSA shows that drivers with THC (the active ingredient in marijuana) in their system have accident responsibility rates below that of drug free drivers.

In fact, a recent study shows that use of medical marijuana has caused traffic related fatalities to drop by up to nine percent in states that have legalized its use. This study, titled “Medical Marijuana Laws, Traffic Fatalities, and Alcohol Consumption”, conducted by Mark Anderson and Daniel Rees in November 2011, shows that increased marijuana use amongst adults has decreased alcohol related traffic deaths in said states. This study provides solid evidence that marijuana is not only a safe substitute for alcohol, but it also makes for more safer drivers.

“Marijuana users often say that when they are high, they feel like they are driving 80 miles per hour but actually are only going 30 miles per hour,” CEO James Shaffer says, “when somebody is drunk driving, on the other hand, they often feel like they are driving 30 miles per hour but are actually driving 80 miles per hour. This is what makes alcohol dangerous behind the wheel, and marijuana safe.”

As an auto insurance quote provider, says that marijuana use can also have an indirect effect on insurance rates. Because of the correlation between marijuana use and accident responsibility rates, they say, marijuana users, as a whole, can expect to see lower insurance rates than non-marijuana users.

“The hypocrisy of it all is that if you get caught driving under the influence of marijuana, you will be fined and perhaps thrown into jail. Whats worse is that your insurance rates will definitely increase due to the traffic violation,” says Mr. Shaffer, “What law enforcement agencies and insurers do not understand is that driving while high is actually a safe activity. I guess the key to safer driving is to use marijuana, but to do it under-wraps.” is an auto insurance quote provider operating out of Manhattan, NY. In business since 2008, they offer free insurance quotes online to United States users. In addition, releases reports and studies on the automobile and insurance industries.

Reasons Why Marijuana Users Are Safe Drivers

Driving while intoxicated is a well known way to cause an accident on the road. Although not as common, you can be charged with that offense for more than just drinking alcohol. It also includes anything else that causes impairment, such as drugs (whether they are legal ones or not), including marijuana.

However, 20 years of study has concluded that marijuana smokers may actually be getting a bad rap and that they may actually have fewer accidents than other drivers. There have been several studies done over the past 20 years and every one of them has revealed that using marijuana actually has a very minor, if any, effect on the ability of a person to drive a car or other vehicle.

Marijuana, Alcohol users Use Products Differently

Research studies showed that if a comparison was done between how drivers who had been drinking alcohol and those who had been using marijuana, it showed that the pot users were in fewer crashes.

Why is this so?

Researchers believe it is because of the way people consume the two products, as alcohol drinkers usually do their drinking out in public and then try to drive home, while pot smokers usually smoke at home and don’t try to drive, meaning fewer are involved in driving accidents in the first place.

Research also shows that while drunk drivers usually drive faster and don’t understand that their driving skills are messed up, the drivers that have been smoking marijuana actually tend to drive slower and stay away from risky behavior.

These and other tests on marijuana smoking and driving were done in different places all over the world, including Canada, Australia, the Netherlands, the United States, and the UK with the following results:

Results of Major Studies on Marijuana and Driving

The research that has been done on this phenomenon of marijuana smoking and driving has shown some interesting results:

Research studies in the Netherlands at the Dutch Institute for Road Safety Research that drivers with blood alcohol rates of .5 percent up to .8 percent had accidents five times more than other drivers, and if it was higher amounts of alcohol, the results were accidents happening up to 15 times more often. But, the marijuana smokers actually showed these drivers posed NO risk at all!

Top 10 Reasons Marijuana Users Are Safer Drivers

When you combine all of the main results of these two decades worth of scientific research studies, the following 10 reasons marijuana drivers are safer than drunk drivers comes out like this:

1. Drivers who had been using marijuana were found to drive slower, according to a 1983 study done by U.S. National Highway Transportation Safety Administration (NHTSA). This was seen as a factor in their favour, since drivers who drank alcohol usually drove faster and that is part of the reason they had accidents.

2. Marijuana users were able to drive straight and not have any trouble staying in their own lanes when driving on the highway, according to a NHTSA done in 1993 in the Netherlands. The study determined also that the use of marijuana had very little affect on the person’s overall driving ability.

3. Drivers who had smoked marijuana were shown to be less likely to try to pass other cars and to drive at a consistent speed, according to a University of Adelaide study done in Australia. The study showed no danger unless the drivers had also been drinking alcohol.

4. Drivers high on marijuana were also shown to be less likely to drive in a reckless fashion, according to a study done in 2000 in the UK by the UK Transport Research Lab. The study was done using driver on driving simulators over a period of a month and was actually undertaken to show that pot was a cause for impairment, but instead it showed the opposite and confirmed that these drivers were actually much safer than some of the other drivers on the road.

5. States that allow the legal use of marijuana for medical reasons are noticing less traffic fatalities; for instance, in Colorado and Montana there has been a nine percent drop in traffic fatalities and a five percent drop in beer sales.

The conclusion was that using marijuana actually has helped save lives! Medical marijuana is allowed in 16 states in the U.S.

6. Low doses of marijuana in a person’s system was found by tests in Canada in 2002 to have little effect on a person’s ability to drive a car, and that these drivers were in much fewer car crashes than alcohol drinkers.


7. Most marijuana smokers have fewer crashes because they don’t even drive in the first place and just stay home thus concluded more than one of these tests on pot smoking and driving.

8. Marijuana smokers are thought to be more sober drivers. Traffic information from 13 states where medical marijuana is legal showed that these drivers were actually safer and more careful than many other drivers on the road.

These studies were confirmed by the University of Colorado and the Montana State University when they compared a relationship between legal marijuana use and deaths in traffic accidents in those states. The studies done by a group called the Truth About Cars showed that traffic deaths fell nine percent in states with legal use of medical marijuana.

9. Multiple studies showed that marijuana smokers were less likely to be risk takers than those that use alcohol. The studies showed that the marijuana calmed them down and made them actually pay more attention to their abilities.All of these tests and research studies showed that while some people think that marijuana is a major cause of traffic problems, in reality it may make the users even safer when they get behind the wheel!

10. Marijuana smoking drivers were shown to drive at prescribed following distances, which made them less likely to cause or have crashes.

Every test seemed to come up with these same results in all of the countries they were done in. Even so, insurance companies will still penalize any driver in an accident that has been shown to have been smoking pot, so this doesn’t give drivers free reign to smoke pot and drive.

So, the bottom line is that while alcohol has been shown in every single incident to have major problems and to have caused countless traffic crashes and fatalities, pot smoking overall has had none of these issues and in fact may make drivers pay more attention, drive slower and straighter and perhaps even stay home so they can’t be in an accident at all!

Auto Insurance Study

UI studies impact of marijuana on driving

First-of-its-kind study at University of Iowas National Advanced Driving Simulator shows how marijuana and marijuana with alcohol impact driving

new study conducted at the University of Iowa’s National Advanced Driving Simulator (NADS) has found drivers who use alcohol and marijuana together weave more on a virtual roadway than drivers who use either substance independently. However, the cocktail of alcohol and marijuana does not double the effect of the impairment.

“What we saw was an additive effect, not a synergistic effect, when we put them together,” says Tim Brown, associate research scientist at NADS and co-author of the study. “You get what you expect if you take alcohol and cannabis and merge them together.”

The study, which was published June 23 in Drug and Alcohol Dependence, also found that participants who consumed only alcohol weaved more during a 35- to 45-minute simulated driving test than those who consumed only vaporized cannabis. Gary Gaffney, associate professor of psychiatry in the UI Carver College of Medicine, is the study’s principal investigator. It’s co-principal investigators are Brown and Gary Milavetz, associate professor and head of the division of Applied Clinical Sciences in the College of Pharmacy.

The results are part of a larger study—the first of its kind to analyze the effects of inhaled cannabis on driving performance—sponsored by the National Highway Traffic Safety Administration, National Institute of Drug Abuse, and the Office of National Drug Control Policy. The UI was selected for the research because of the NADS authenticity to real driving and the universitys expertise in medicine, pharmacy, and engineering. The NADS is the only simulator of its kind that is publicly owned.

The outcomes could help shape future legislation in the United States where some experts say policies on drugged driving are woefully behind.

To date, medical marijuana is legal in 23 states and the District of Columbia while marijuana has been approved for recreational use in four states and D.C. Since legalizing medical marijuana, Colorado has reported an increase in driving under the influence of cannabis cases and fatal motor vehicle crashes with cannabis-only positive drivers while states without legalized marijuana have experienced no significant change in cannabis-related crashes.

In 2014, the National Highway Traffic Safety Administration’s Roadside Survey of Alcohol and Drug Use by Drivers found the number of drivers with alcohol in their system had declined by nearly one-third since 2007. However, that same survey found the number of weekend nighttime drivers with evidence of drugs in their system climbed from 16.3 percent in 2007 to 20 percent in 2014. The number of drivers with marijuana in their system grew by nearly 50 percent.

Brown says plenty of research has been done on the effects of drinking alcohol and driving, but little has been done to measure the effects of using marijuana and driving.

“Alcohol is the most common drug present in the system in roadside stops by police; cannabis is the next most common, and cannabis is often paired with alcohol below the legal limits,” Brown says. “So the questions are: Is alcohol an issue? Is cannabis an issue? We know alcohol is an issue, but is cannabis an issue or is cannabis an issue when paired with alcohol? We tried to find out.”

Researchers selected 18 participants—13 men and five women—between the ages of 21 and 37 who reported drinking alcohol and using marijuana no more than three times a week. After spending the night at the University of Iowa Hospital and Clinics to ensure sobriety, participants arrived at NADS for six “dosing visits.”

First, participants were given 10 minutes to drink a mixed drink with alcohol or plain juice in an alcohol-rimmed glass and topped with alcohol to mimic alcohol taste and odor. The idea was to get the participants blood alcohol level to about .065 percent at the start of the simulated drive.

Next, they were given 10 minutes to inhale a placebo or vaporized cannabis using a vaporizing system designed in Germany called “Volcano Medic ™.”

Cannibis study graph
A comparison of lane weaving observed in a simulated driving study between common legal drunk driving limits (BrAC) and the blood concentration of THC that produce a similar amount of lane weaving.

Once in the simulator—a 1996 Malibu sedan mounted in a 24-feet diameter dome—the drivers were assessed on weaving within the lane, how often the car left the lane, and the speed of the weaving. Drivers with only alcohol in their systems showed impairment in all three areas while those strictly under the influence of vaporized cannabis only demonstrated problems weaving within the lane.

Drivers with blood concentrations of 13.1 ug/L THC, or delta-9-tetrahydrocannabinol, the active ingredient in marijuana, showed increased weaving that was similar to those with a .08 breath alcohol concentration, the legal limit in most states. The legal limit for THC in Washington and Colorado is 5 ug/L, the same amount other states have considered.

The study also found that analyzing a driver’s oral fluids can detect recent use of marijuana but is not a reliable measure of impairment.

“Everyone wants a Breathalyzer which works for alcohol because alcohol is metabolized in the lungs,” says Andrew Spurgin, a postdoctoral research fellow with the UI College of Pharmacy. “But for cannabis this isnt as simple due to THCs metabolic and chemical properties.”

Additional authors on the study include Rebecca L. Hartman (lead author), National Institute on Drug Abuse; Milavetz; Spurgin; Russell S. Pierce, VariableSolutions, USA; David A. Gorelick, National Institute on Drug Abuse; Gaffney; and Marilyn A. Huestis (corresponding author), National Institute on Drug Abuse.

Kyla Lee: Vancouver Criminal Lawyer Blog

The Twelve Weeks of DRE-Mas: Eye Examinations


After the preliminary steps are done, taking first pulse and an initial examination, the DRE officer is then able to move on to the more complex eye examinations. The results of these examinations are said to be used to help the DRE officer determine whether a person is impaired by a drug, and identify the class of drugs that is causing the impairment.
Eye examinations are particularly interesting because they do not actually say much about impairment at all. What they do say a lot about is the condition of a person’s eyeball and whether that person may have suffered head injuries, has or is suffering a stroke or a seizure, or whether a person may have neurological conditions. Of course, a police officer is in no position to determine any of this.
So read on to find out the three types of eye examinations that are used in the DRE Evaluation.

Horizontal Gaze Nystagmus Test

Ah, another example of the DRE evaluation being used to look for symptoms that are present with alcohol in order to detect drug impairment. The Horizontal Gaze Nystagmus test was originally designed by NHTSA for the purposes of looking for alcohol impairment. In fact, the statistics relied on by NHTSA claim that this test is 88% reliable at identifying alcohol-impaired drivers if four or more clues are present. Clues, by the way, are the parts of the test the officer is designed to look for in the case.
The problem with the HGN is that, by and large, it is not expected to be present with drug impairment. For example, only CNS depressants, inhalants, and PCP will produce HGN. And bear in mind too that CNS depressants include alcohol. I have to wonder why a DRE test is required at all in cases of people who are impaired by PCP. I mean, have you ever seen what goes down with PCP use? A DRE evaluation is definitely not necessary.
The HGN is administered by an officer with a pen or a pen like object, known as a stimulus. Essentially, the stimulus is passed in front of the eyes and held at certain points so that officers can assess whether there is any involuntary jerking of the eyeball. But there are a number of limitations on its use. And when administered incorrectly, which apparently occurs around 90% of the time, the test does not produce reliable information. The stimulus must be a certain distance from the person’s eyes not too far or too close, level with their eyes not too high or too low, moved not too slowly and not too quickly, and moved to the just right spot for measuring whether there is distinct and sustained nystagmus at maximum deviation, not too far or not far enough.

It’s like Goldilocks and the Three Bears, but for your eyeballs.

But nystagmus is not just a symptom of drug use. It is also a symptom of all sorts of other medical conditions, head injuries, and can even be hereditary. The presence or absence of nystagmus, with so many other explanations simply does not reliably indicate or even hint at impairment, much less impairment by a drug.

Vertical Gaze Nystagmus

This one is not much better. In fact, it’s basically the Horizontal Gaze Nystagmus but in the opposite direction. Instead of the officer engaging in moving the stimulus back and forth, the stimulus is moved up and down. Except, medical experts aren’t entirely certain why vertical gaze nystagmus appears when it does appear. And the answer is not always impairment by drugs.

As with the HGN, the VGN doesn’t really lend much information to the DRE officer about what drugs might be the cause of what they are seeing. It is said to be present at high concentrations of CNS depressants and inhalants, and again present with PCP. Pro tip: if you’ve got a person on PCP to the stage where they are now willingly taking the VGN evaluation step, they’re not on PCP. So together the VGN and HGN just really seem to act as confirmation bias of one another.

Given the absence of solid medical explanation for why VGN may appear in some people, it is dangerous if not foolhardy to effectively guess that it means a person has taken a high dose of CNS depressants, inhalants, or is on PCP simply because their eyeballs move around in a weird way.

Lack of Convergence

This one is really simple. So simple, in fact, that you probably determined whether you had issues with lack of convergence on the playground in elementary school. It is merely the ability to cross your eyes. Apparently, according to the infinite scientific wisdom of NHTSA, a person who is using PCP, inhalants, CNS depressants, or cannabis will not be able to cross their eyes.

Lack of convergence is, interestingly, the only eye movement-related cannabis symptom that is included in the DRE matrix for the assessment of the results. Which leads me to think that the NHTSA DRE developers were taking their opinions about eye movement and cannabis from this slightly paranoid Grasscity forum question.

And, if you’re sensing a trend, these lack of convergence tests are also consistent with known medical conditions that do not have known causes or explanations. Maybe it is smoking too much cannabis, but I highly doubt it.

One of the concerning aspects about the eye tests — and you’ll note heavy reliance on the eyeballs overall in the DRE program — is that, as my older readers will appreciate, your eye function deteriorates as you age. And so does your ability to stare at a book or TV screen or cross your eyes or follow a stimulus with smooth pursuit. But aging is not drug impaired driving, and yet the DRE appears designed to make it out as though it is.

Next week we will cover the divided attention psychophysical tests. Sounds super fancy, but I promise they are anything but. Check back then.

Read – Kyla Lee’s Blog


Evidence Review
Canadian Drug Policy Coalition (CDPC)
Simon Fraser University
March 27, 2017


  • Rielle Capler, MHA Ph.D. – Candidate, University of British Columbia
  • Dan Bilsker, Ph.D. – Clinical Assistant Professor, Faculty of Medicine, University of British Columbia
  • Kelsey Van Pelt, BSc MPH – Candidate, Simon Fraser University
  • Donald MacPherson Executive Director, Canadian Drug Policy Coalition (CDPC) Adjunct Professor, Faculty of Health Sciences, Simon Fraser University

Download PDF – Click Here

A new Statistics Canada survey has found about 1.4 million Canadians reported they had been a passenger in a vehicle driven by someone who had consumed cannabis in the previous two hours.

In addition, one in seven cannabis users with a driver’s licence said they had got behind the wheel at least once within two hours of using the drug in the past three months. Men were nearly two times more likely than women to report this behaviour.

With the Trudeau government’s Cannabis Act set to become law on Oct. 17, Statistics Canada has begun measuring the social and economic impacts of legalized cannabis through a quarterly national cannabis survey.

The second quarter data found that about 4.6 million people nationally, or close to 16 per cent of Canadians aged 15 and up, reported using cannabis in the prior three-month period. This was similar to what was reported in last quarter.

The vast majority of respondents — 82 per cent — also said they probably wouldn’t increase their consumption once pot is legalized, which was also relatively unchanged over last quarter.

The latest data was collected from mid-May to mid-June and includes data for the provinces, as well as the territorial capitals.

Globe and Mail article

From the second-story window of the High Life Social Club in Halifax, which is planted discreetly above a café serving all-day breakfast, the owner Chris Henderson points to the bus stop across the street. Until a few weeks ago, it displayed a poster for every departing patron of his cannabis-friendly lounge to see, part of a citywide public-education campaign to prepare for the legalization of marijuana on Oct. 17.

“Drive better on weed?” the poster asked, with a touch of snark, as if you’d have to be on drugs not to know the right answer. As it happens, that’s a question easily answered on a warm Tuesday evening in July, doused in the sweet, skunky perfume of pot, with club members drinking bottled water between hits on a water bong.

Turns out, they think they do. The science, however, begs to differ.

For instance, a 21-year-old High Life regular, and early childhood educator, lounging on a black couch beside a large mural of the caterpillar from Alice in Wonderland, offered an anecdote about a friend who passed her driving test while stoned. (The woman asked not to be identified; her employers, she noted, wouldn’t be so cannabis friendly.) After a day chasing toddlers, she says, smoking a joint helps her focus on the road. Most nights at the lounge, she waits an hour or so, and drives home. Anyway, she insists, if you find yourself too stoned to drive, just pull over and wait 15 minutes to sober up.

A retired telecom technician in his 60s wanders over and joins the conversation. While he now bikes everywhere, he describes driving stoned regularly, with no problems. (Not so with alcohol, he notes, which resulted in an impaired-driving conviction three decades ago, and one accident.) Compared to drinking, he says to general agreement, pot keeps you more chilled out on the road – and less likely to rage at other drivers.

Later in the evening, a 19-year-old engineering students fields questions about his own habits at the counter where chocolate is for sale. He would never drink and drive, he explains, and wouldn’t have driven when he first started using cannabis. But six months in, he figures he knows his limit – today, he says, he wouldn’t take a road trip without a joint. It’s not dangerous, he claims. Among his evidence: He always stop at stop signs.

Collectively, they are candid and amiable – and working hard to convince a stranger that they’re upstanding, clearly aware that their drug of choice suffers from some bad PR.

But none of these assertions are supported in the growing research on cannabis. The sum of all the science – the driving simulations and on-road experiments, the cognitive testing, even the albeit mixed crash-collision statistics – shows clearly that there are far from “zero problems” with driving high.

Marilyn Huestis, a leading American expert who has been studying cannabis for 30 years, including offering advice on driving issues to Canadian policy makers, says that for non-daily users, it takes six hours for the effects of one joint to completely disappear. That’s even if your blood level of THC, the drug’s psychoactive ingredient, is low – an issue that creates additional complications for police testing suspect drivers for legal limits, and a public trying to abide by them. Needless to say, if you’re “too stoned” behind the wheel, don’t expect a 15-minute pause to make you safe. Occasional users perform more poorly than regular users in studies. But even for the pros, the danger exists – though, as it happens, familiar stop signs may be the least of it.

At the same time, research does suggest that people who are stoned are more aware of their impairment than those who’ve been drinking – a self-safety check, undeniably, in their favour. Traffic collision statistics show that driving high increases the risk of a crash or collision, although by how much is still the subject of debate, and the overall risk is nowhere near as high as alcohol. For instance, a French study of drivers in fatal collisions, found those with cannabis in their blood were twice as likely to be found culpable for the crash than sober driver, compared to nine times for those with alcohol in their system.

According to a 2016 study by Norwegian researchers, which updated earlier findings and analyzed 13 international crash-collision studies between 1982 and 2015, cannabis use increases the risk of a crash by about 30 per cent, compared with a sober, attentive driver. Drunk drivers over the legal limit, on the other hand, are more than 600 times more likely to crash, according to report by the National Highway Traffic Safety Administration (NHTSA) in the United States.

In 2016, the NHTSA was also behind what is considered one of the most comprehensive – and controversial – experiments to assess the risk of marijuana and driving. Researchers investigated crashes in real time in Virginia, 24 hours a day for 20 months. They compared the crashed drivers with THC to a control group of drivers stopped in the same location, at the same time as the crash, who agreed to be screened for cannabis. Once researchers adjusted for age and gender – particularly, young and male – and the presence of alcohol, they found no increased risk of collisions compared with drug-free drivers. But despite its great design, there were some flaws in the study’s execution, says Mark Asbridge, the MADD Canada professor in impaired-driving research and prevention at Dalhousie University. The location was near a military base, which regularly tested soldiers for the presence of drugs, an external influence on driving behaviour, and the control-study drivers could refuse to participate, reducing the sample of those with drugs in their system. As with most cannabis studies, there was a delay or problem in getting blood samples, especially for more serious crashes. Even the authors of the U.S. study warned not to interpret their findings – one sample of drivers in one location – to be saying it was safe to drive high.

One of the complications of studying cannabis is how often it is combined with alcohol, a particularly dangerous driving cocktail, the research suggests. In the French study on fatal crashes, for example, drivers who had consumed both alcohol and cannabis were 14 times more likely to be found responsible for the crash when compared with sober drivers – much higher than those who had consumed either drug on its own.

Still, these mixed results suggest why, according to a September 2017 survey commissioned by Public Safety Canada, a hearty portion of Canadians believe that driving high isn’t so bad. Twenty-eight per cent of the 2,132 respondents said they’d driven high, and of those, 17 per cent said the influence of cannabis “posed no real risks.” Nearly one in 10 of all respondents believe cannabis makes a person “a better driver.” For Canadians under the age of 24, risk was perceived to be even lower. In a 2017 large-scale Ontario survey, 8 per cent of teenagers admitted to driving an hour after using cannabis – compared with 4 per cent who said they had driven drunk. The good news is that the driving-high figure has fallen slowly since 2011, when the question was first asked. The bad news is, in the Public Safety survey, 43 per cent of Canadian said they didn’t know how long to safely wait after a joint before driving, with young people more likely to predict shorter wait times.

“We used to say the same thing about drinking and driving. ‘I can have a few drinks and it relaxes me.’ ‘I can have one for the road,’” says Robert Mann, a researcher at the Centre for Addiction and Mental Health. Hopefully, he says, changing attitudes about marijuana won’t take as long. “The clear message is that using cannabis increases your risk of an accident.”

Collision stats clump drivers together to see a highway of cars. They aren’t measuring the safety of individuals, on their own route home. Occasional users appear to score worse when acutely stoned than more frequent users who may have developed a tolerance. (Although, Dr. Heustis notes that the cognitive deficits that result from chronic use may also lower driving skills.) New drivers are likely to be more challenged than veterans. An issue with all marijuana research to date, is that it’s usually focused on smoking the drug, typically at lower THC levels than today’s versions. It’s not clear the difference that newer forms of consumption will have on driving, including edibles, which make a user high more slowly, and can lead to people ingesting too much.

Even with those limitations, however, driving simulations in the lab, show that cannabis clearly impairs drivers, if somewhat differently than alcohol. Drunks put their foot on the gas; stoners dance their toes on the brake. They both weave on the road, but the latter does it more often at a safer speed. The notion that being high “makes you a better driver” likely originates here – cannabis users appear to compensate for their impairment with some caution, such as putting more space between the car in front of them.

So on a quiet ride on a familiar route, a driver under the influence of cannabis may be able to get home without incident. But driving, as Dr. Heustis notes, is marked by unexpected events – a kid riding their bike into the street, an elderly man dropping his key on the crosswalk, another swerving car. Being high, she says, makes it harder for drivers to compensate for surprises – in simulations, marijuana slows reaction times, divides a driver’s attention and makes decision-making foggy. For example, she says, in lab tests, cannabis users can add a row of numbers as well as a sober person – but throw in a complicated problem and they falter. With driving, Dr. Heustis says, they may be concentrating so hard at the just-getting-it-done task, that a sudden rush of complex information is overwhelming.

Back at the High Life Social Club, Chris Henderson, the businessman with a smoking angel tattoo dancing up his neck and a devil staring from his back, tries to navigate the views of his patrons, and the fears of a worried public. He has a marijuana prescription to deal with chronic pain – he could consume up to six joints a day, although he usually takes much less. Even a few hours after using, he is “100-per-cent confident” he is safe on the road. He’d have no problem taking a roadside test, he says, but he worries about being charged for having THC in his blood, even when he is not impaired.

The new law is “better-safe-than-sorry legislation,” by his way of thinking. “But the most important thing is that the roads remains safe,” he says. “If that means people taking a cab because they smoke a joint, that’s probably not a bad thing.”

Globe and Mail article

Cannabis and driving: Breaking down Canada’s new limits

What’s the new legal limit for cannabis while driving? The government has set 2 nanograms of THC per millilitre of blood as a summary conviction, with up to a $1,000 fine. At 5 ng, a driver would be charged with a criminal offence – similar to the blood alcohol limit of .08 – with a maximum penalty of 10 years in prison. And there’s also a more serious penalty if you are caught with a combined blood limit of .05 and 2.5 ng of cannabis. There is no exception for medicinal users.

How many puffs is that? Unlike alcohol, there’s no clear guideline, and the government hasn’t provided any. It depends on how much and how deeply you inhale, the strength of the cannabis you use and how you consume it, your experience using and your individual characteristics. For edibles, which take longer to take effect, it is even trickier.

What the science says: Research shows that a driver’s THC (the psychoactive ingredient in the drug) blood levels is an unreliable indicator of impairment. While alcohol is absorbed and eliminated in the blood at a linear rate, blood levels of THC fall quickly after smoking and then flatten out. This means people may feel the most high even when their THC blood level is at a very low rate. Since THC leaves the blood so quickly – but remains in the brain for a longer period – a higher legal limit may not capture drivers who are still seriously impaired, especially given the added delay in collecting blood samples. In any event, says Marilyn Huestis, a leading American cannabis researcher, there is no one simple measurement of THC at which everyone using cannabis will be impaired.

How Canada’s law compares: While some U.S. states and countries have zero-tolerance limits for cannabis, Canada’s new legal limits are roughly in line with other jurisdictions, such as Colorado and Washington, where cannabis is legal. Britain, however, allows for a medical defence if the driver can demonstrate they were not impaired.

So what if I use marijuana medicinally? This is a real issue, one that experts have said will probably need to be resolved with court cases. People taking cannabis regularly may have a residual dose of THC in their blood even though they haven’t used recently and are not impaired. Since measuring drugs amounts is complicated, New Zealand’s policing approach, for instance, has emphasized evidence of impairment, and not relied so heavily on blood tests.

What if I get stopped? As before legalization, a police officer may give you a three-part sobriety test – walk the line, balance on one foot, track the finger – if they have reason to believe you have been using cannabis, or any drug that is making you a danger on the road. Police will also be able to administer a saliva test once they are approved and distributed. If you fail those tests, a more detailed interview happens back at the station, but, because THC levels fall so quickly, the new law also allows police to skip right to a blood test.

What’s my best strategy? The guideline recommended by the Canadian Centre for Addiction and Mental Heath – and in research by the National Institute for Drug Abuse in the United States – is to wait at least six hours before driving after a smoking a joint. If you use only occasionally, studies suggest, the effect on your driving will be worse than more frequent users. Be extra careful mixing marijuana with alcohol – when combined, research shows, they may impair drivers much more than either drug alone.

Globe and Mail article

Experts raise concerns about Ottawa’s planned crackdown on drug-impaired drivers

Bill C-46, which would create new drug-impaired driving offences, is currently being studied in the Senate, where there is growing pressure on senators to amend the proposed legislation before it comes into law. The government wants the new rules in place before cannabis is legalized for recreational use, a move expected in late summer.

According to experts, Bill C-46 sets limits for levels of THC, the primary psychoactive compound in cannabis, that do not determine whether a driver is impaired or not. Cannabis acts differently on the body from alcohol, and there is no exact link between driving abilities and THC levels, as measured in nanograms per millimetre (ng) of blood.

The “per se” limits for alcohol (80 milligrams of alcohol in 100 millilitres of blood) have been upheld in court, but the limits for cannabis have not been tested in court. Some frequent users have constant levels of THC and are not actively impaired, while others may be impaired with low levels of THC.

“As toxicologists, we’re not big on ‘per se’ numbers for drugs because drugs are very different from alcohol on how they impair people, the tolerance and the wide spectrum of tolerance that exists between different individuals,” D’Arcy Smith, a member of the RCMP’s drug evaluation and classification program, told senators last month.

Amy Peaire, who chairs the drugs and driving committee at the Canadian Society of Forensic Science, added impairment depends on a variety of factors, including whether cannabis was smoked or eaten. Cannabis is fat soluble, which means blood concentration levels vary between individuals.

“Unlike alcohol in which you can have blood concentrations which have links to impairment, that’s not the same for THC because there’s not a good correlation between impairment and blood concentration,” said Ms. Peaire.

Justice Minister Jody Wilson-Raybould has defended her government’s approach, stating it relied on scientific evidence, including the work of Mr. Smith and Ms. Peaire.

“We’re moving forward on the drug levels that we have in C-46. The levels have been set and based in large part on the advice provided to us by the drugs and driving committee. The science around drug levels is something that continues to evolve and we’ll continue to engage with the committee,” Ms. Wilson-Raybould told reporters.

Under Bill C-46, three new offences would be created:

    • Having a THC level between 2 and 5 ng, punishable by a fine of up to $1,000;
    • Having a level above 5 ng, punishable by a fine of $1,000 for a first offence and escalating penalties for repeat offenders;
  • Having a blood alcohol concentration of 50 milligrams per 100 mL of blood in addition to a THC level superior to 2.5 ng, with the same penalties as the previous offence.

Ms. Wilson-Raybould said the best way to prevent drug-impaired driving is simply to stay off the road after consuming cannabis.

“Until we have definitive scientific evidence around what is a safe level, we’re proceeding on a precautionary basis, saying there is no safe level,” Ms. Wilson-Raybould said.

But lawyers warned the government the new regime will be hard to enforce, with legal challenges guaranteed to clog up Canadian courts already beset by delays.

“The [Canadian Bar Association] does not view Bill C-46 as offering any significant improvement over the existing legislation, certainly not one that would offset its negative impact on justice efficiencies,” spokeswoman Kathryn Pentz told senators.

Ms. Pentz added the new law is bound to be challenged in court and that prosecutors will be hard-pressed to defend the measures.

“It has to be evidence-based. At this point and time, the experts are saying we really cannot get a correlation between a level of drugs in one’s system and a level of impairment,” she said.

Conservative Senator Claude Carignan has expressed serious reservations about Bill C-46, saying the best way to determine whether drivers are impaired is through certified drug recognition experts (DRE). However, the process to become a DRE is long and mostly requires training in the United States, leaving Canada with a shortage with only a few months to go before legalization.

“The solution will be to present an amendment to Bill C-46 to suspend the application of the ‘per se’ limits up until the moment that scientific evidence backs up their use, and to rely solely on DREs in the meantime,” Mr. Carignan said.

Kyla Lee, a Vancouver-based defence lawyer, said the law would be more likely to withstand a constitutional challenge if DREs were used in every case before charges are laid.

“I believe it would be more likely to withstand Charter scrutiny,” she told senators.

The Globe and Mail


Evidence Review
Canadian Drug Policy Coalition (CDPC)
Simon Fraser University
March 27, 2017


  • Rielle Capler, MHA Ph.D. – Candidate, University of British Columbia
  • Dan Bilsker, Ph.D. – Clinical Assistant Professor, Faculty of Medicine, University of British Columbia
  • Kelsey Van Pelt, BSc MPH – Candidate, Simon Fraser University
  • Donald MacPherson Executive Director, Canadian Drug Policy Coalition (CDPC) Adjunct Professor, Faculty of Health Sciences, Simon Fraser University

Download PDF – Click Here

First of its kind study

First of its Kind Study Finds Virtually No Driving Impairment Under the Influence of Marijuana

As cannabis prohibition laws crumble seemingly by the day, it’s allowing more research to be performed on this psychoactive substance that has long been a part of the human experience.

The first study to analyze the effects of cannabis on driving performance found that it caused almost no impairment. The impairment that it did cause was similar to that observed under the influence of a legal alcohol limit.

Researchers at the University of Iowa’s National Advanced Driving Simulator carried out the study, sponsored by National Highway Traffic Safety Administration, National Institute of Drug Abuse, and the Office of National Drug Control Policy

“Once in the simulator—a 1996 Malibu sedan mounted in a 24-feet diameter dome—the drivers were assessed on weaving within the lane, how often the car left the lane, and the speed of the weaving. Drivers with only alcohol in their systems showed impairment in all three areas while those strictly under the influence of vaporized cannabis only demonstrated problems weaving within the lane.

Drivers with blood concentrations of 13.1 ug/L THC, or delta-9-tetrahydrocannabinol, the active ingredient in marijuana, showed increased weaving that was similar to those with a .08 breath alcohol concentration, the legal limit in most states. The legal limit for THC in Washington and Colorado is 5 ug/L, the same amount other states have considered.”

As expected, there was impairment in all areas when alcohol and cannabis were mixed. But cannabis itself, when taken in moderate amounts, seems to cause no significant driving impairment.

In fact, some would argue that it makes them drive safer or slower.

The study’s findings further illuminate the fact that alcohol is a much more dangerous drug than cannabis, and somehow the former is legal while the latter is not.

With cannabis being decriminalized across the country, law enforcement will be getting their “rules and regulations” in place for the driving masses. They should be based on science and not Reefer Madness mentalities.

Another important finding should deter any attempts to deploy instant roadside tests for THC-blood levels.

“The study also found that analyzing a driver’s oral fluids can detect recent use of marijuana but is not a reliable measure of impairment.

“Everyone wants a Breathalyzer which works for alcohol because alcohol is metabolized in the lungs,” says Andrew Spurgin, a postdoctoral research fellow with the UI College of Pharmacy. “But for cannabis this isn’t as simple due to THC’s metabolic and chemical properties.”

Drug War Facts

Relationship Between Medical Marijuana Laws (MMLs) and Traffic Fatalities in the US

“Our study suggests that, on average, MMLs are associated with reductions in traffic fatalities, particularly pronounced among those aged 25 to 44 years, a group representing a great percentage of all registered patients for medical marijuana use,29 and with increased prevalence of marijuana use after the enactment of MMLs.30 Although increases in marijuana use following the establishment of marijuana dispensaries could reduce the occurrence of alcohol-related mortality by reducing the number of drivers driving under the influence of alcohol, other simultaneous factors at the state and local levels also may be responsible for these changes in traffic fatalities. Our findings show great heterogeneity of the MML–traffic fatalities associations across states, suggesting the presence of these other mechanisms. This is important for policy development and for the debate of the enactment or repealing of MMLs, given that alternative local strategies such as stronger police enforcement and programs aiming to reduce impaired driving involving any substance use could be local factors linked to reductions in traffic fatalities in MML states.”

Julian Santaella-Tenorio, Christine M. Mauro, Melanie M. Wall, June H. Kim, Magdalena Cerdá, Katherine M. Keyes, Deborah S. Hasin, Sandro Galea, and Silvia S. Martins. US Traffic Fatalities, 1985–2014, and Their Relationship to Medical Marijuana Laws. American Journal of Public Health: February 2017, Vol. 107, No. 2, pp. 336-342. doi: 10.2105/AJPH.2016.303577
Click Here – for more information …

Crash Fatality Rates After Recreational Marijuana Legalization in Washington and Colorado

Accepted: April 11, 2017

Published Online: July 12, 2017


Objectives. To evaluate motor vehicle crash fatality rates in the first 2 states with recreational marijuana legalization and compare them with motor vehicle crash fatality rates in similar states without recreational marijuana legalization.

Methods. We used the US Fatality Analysis Reporting System to determine the annual numbers of motor vehicle crash fatalities between 2009 and 2015 in Washington, Colorado, and 8 control states. We compared year-over-year changes in motor vehicle crash fatality rates (per billion vehicle miles traveled) before and after recreational marijuana legalization with a difference-in-differences approach that controlled for underlying time trends and state-specific population, economic, and traffic characteristics.

Results. Pre–recreational marijuana legalization annual changes in motor vehicle crash fatality rates for Washington and Colorado were similar to those for the control states. Post–recreational marijuana legalization changes in motor vehicle crash fatality rates for Washington and Colorado also did not significantly differ from those for the control states (adjusted difference-in-differences coefficient = +0.2 fatalities/billion vehicle miles traveled; 95% confidence interval = −0.4, +0.9).

Conclusions. Three years after recreational marijuana legalization, changes in motor vehicle crash fatality rates for Washington and Colorado were not statistically different from those in similar states without recreational marijuana legalization. Future studies over a longer time remain warranted.

For more information follow LINK … Recreational Marijuana Legalization Driving


WATERLOO, ON, JUNE 27, 2017 – Canadians for Fair Access to Medical Marijuana (CFAMM), a national non-profit organization, released a first-of-its-kind preliminary research review on medical cannabis impaired driving – one of the major public safety concerns stemming from the legalization of non-medical cannabis.

The review situates the use of cannabis for medical purposes among research related to policy, prevalence, and risk of cannabis/THC impaired driving. The 200,000 legally authorized Canadians who are prescribed medical cannabis have important and distinct characteristics including dosing, strains, tolerance, methods of administration, and education received by their prescribing physicians. These factors, explored in the review, set medical cannabis patients apart from non-medical consumers and demonstrate this to be a key area left unexplored in previous impaired driving literature.

This preliminary review offers insight into how cannabis used for medical purposes relates to impaired driving, including the following topics:


While CFAMM is fully against impaired driving and supports responsible driving legislation, the term “impairment” is widely used but is not always clearly defined. When speaking of impairment, crucial to this dialogue is speaking to actualimpairment of cognitive, psychomotor, and other functions necessary to safely drive – not simply a measure of previous use such as the presence of THC in blood. Unlike blood alcohol concentration, which is scientifically linked to levels of impairment, matching levels of impairment to levels of THC in one’s system is still widely debated and has not been studied related to medical cannabis use.


Although many studies have explored the risk of recreational or occasional use of cannabis related to driving impairment, few have studied the risk related to responsible medical use of cannabis. For most patients, the goal of medical cannabis use is not to experience its psychoactive effects, but rather to treat or manage symptoms of an illness using the smallest effective dose. Although it’s a limited example, a past study on the medical use of cannabis (Sativex) for multiple sclerosis identified better driving safety measures after the introduction of cannabis in patients’ treatment regimens, suggesting a need for further research on medical users. It is also important to note that U.S. states have recorded an 8-11% drop in overall traffic fatalities one year following the introduction of medical cannabis legislation.


Many medically authorized Canadians use cannabis daily or near daily to manage symptoms associated with their illness and are expected to follow advice from health care providers. This includes safe-use guidelines, such as waiting 4+ hours after consumption before driving, to help eliminate risk of potential impairment. The metabolism and effects of THC are highly variable from person-to-person and THC can remain detectable within a regular user’s blood for days after last consumption. The government’s proposal, which would set a per se cut-off of 2ng/ml THC at the lower end, means even when patients are not impaired, they would have to stop using their medicine for 3-7+ days before driving.

“Although driving is not a right but a privilege, patients who use cannabis responsibly and are not impaired should still be able to drive without risk or fear of being charged. It is necessary for the government to incentivize further research and include considerations for patients using cannabis. While a strict precautionary approach may be appropriate in light of limited evidence, policymakers have a responsibility to both safeguard road safety and balance the rights of medical cannabis patients to ensure they are not unfairly criminalized by drugged driving laws that do not target impairment.”

– Jonathan Zaid, Lead Author and Executive Director, CFAMM

CFAMM – Click Here

Should Canadian lawmakers reconsider the amount of THC a driver can have in their bloodstream before legalizing cannabis in 2018?

Now here’s a study Canadian lawmakers should read as they consider Bill C46, which seeks to amend the Criminal Code with respect to drug-impaired driving.

study recently published in the American Journal of Public Health has found that states with legalized recreational cannabis do not have a greater rate of car accident deaths than states where cannabis is illegal.

Conducted by doctors and researchers from the University of Texas-Austin and Rice University, the study compared car accident fatalities in Colorado and Washington, where cannabis is legal, to similar data from eight control states where the drug is still prohibited.

Researchers used a federal fatality reporting system to determine the annual number of fatalities from motor vehicle accidents over six years, between 2009 and 2015, in the 10 states.

By comparing year-over-year changes, they found that the number of fatalities did not increase after recreational cannabis was legalized in Colorado and Washington, and was consistent with the number of deaths in the eight control states.

“This is the first time researchers have actually looked at the real-life effects to see if there have been any major population changes in injuries on the road after marijuana was legalized in these states,” lead study author Jayson Aydelotte told KTVU News in Austin last month.

In both Colorado and Washington, drivers with five nanograms of active tetrahydrocannabinol (THC) per millilitre in their bloodstream can be prosecuted for driving under the influence. Some marijuana lobbyists claim this is far too low, as frequent cannabis users can have residual amounts of THC in their bloodstream well above five nanograms—and for days after consumption.

Others argue the amount is too high, especially because the numbers determined are based on policy, instead of evidence of impairment.

Bill C46 currently outlines a limit of just two nanograms of THC per millilitre.

To put that in context, Canadian Olympian Ross Rebagliati won the gold medal for snowboarding in 1998 with more than eight times than what the federal government has suggested, at 17.8 nanograms per millilitre.

Story from the Straight … Cannabis and Driving

New Accident Studies Confirm:
Marijuana a Lesser Driving Hazard Than Alcohol

Drivers Testing Positive in Urine No More Dangerous Than Drug-Free Drivers

Drivers who test positive for marijuana in urine are no more likely to cause accidents than drug-free drivers, according to a study led by Dr. Carl Soderstrom [01] at the University of Maryland School of Medicine (2005). The study examined 2,405 drivers hospitalized in automobile accidents from 1997 through 2001.

   The study investigated the circumstances of each accident to assess which drivers were at fault or culpable. Drivers testing positive for marijuana were found to have no greater culpability than drug-free drivers.   In every age group, alcohol was the drug most strongly associated with crash culpability.  Cocaine users also showed higher crash culpability, especially in the age range of 21-40.

   Significantly, marijuana-using drivers aged 41 to 60 were statistically less likely to be at fault for accidents than drug-free drivers.   Similar results have been suggested in other studies, perhaps because marijuana-using drivers tend to slow down.

   This flatly refutes the rationale for random testing of truck and bus drivers, observed California NORML coordinator Dale Gieringer, Urine tests for marijuana donπt reflect driving impairment. Two other studies [2] have failed to find higher accident rates for drivers testing positive for marijuana in urine.

   An essential reason for these negative results is the reliance on urine tests  to detect marijuana.   Urine tests are poor indicators of impairment because they detect non-psychoactive metabolites that stay in the system for days after marijuana is smoked.  Blood tests, which measure the presence of psychoactive THC, provide a better indication of current impairment.  Usually they register positive for only a few hours after smoking, though low levels of blood THC may persist in heavy users for a day or two. Some though not all studies have found higher accident rates for drivers testing positive for THC in  blood.

In another new accident study [3] the largest yet French researchers examined 10,748 drivers involved in fatal crashes for traces of drugs and alcohol in blood.  The study found that the presence of THC in blood was associated with a somewhat higher risk of responsibility for accidents, but significantly less so than alcohol.  The increased risk for THC was dose-dependent, ranging from 1.6 at trace levels to 3 at the highest levels (above 5 nanograms THC per milliliter of blood).  In contrast, for alcohol the risk ranged from 3 at the lowest levels (below .05% blood alcohol) to over 40 at the highest levels.   The study has proved embarrassing for drug warriors in the French government, who had prematurely rushed to pass a ≥zero tolerance≤ DUI law barring any blood traces of THC before the study was complete.  The study showed that driving with THC in blood was in fact no riskier than driving at blood alcohol levels below .05%, which is legally permitted in France.   The U.S. allows alcohol levels up to .08%.

   Numerous other studies have found that marijuana is a significantly lesser driving hazard than alcohol.   Current scientific evidence shows clearly that a zero tolerance standard for THC in blood is unjustified, argues California NORML coordinator Dale Gieringer. An expert panel report chaired by Dr. Franjo Grotenhermen [4] of the International Association for Cannabis Medicine concluded that levels above 3.5 to 5 nanograms per milliliter of THC in blood are generally indicative of impairment. On the other hand,  there is considerable  evidence indicating that lower levels of blood THC can be consistent with safe driving.


 (1 ) Carl Soderstrom et al, ≥Crash Culpability Relative to Age and Sex for Injured Drivers Using Alcohol, Marijuana or Cocaine,≤ 49th Annual Proceedings of the Association for the Advancement of Automotive Medicine, Sept. 13-14, 2005.

(2) SR Lowenstein  and J Koziol-McLain Drugs and traffic crash responsibility: a study of injured motorists in Colorado, J Trauma 50(2):313-30 (2001); and KLL Movig et al, Psychoactive substance use and the risk of motor vehicle accidents [in the Netherlands], Accident Analysis and Prevention 36: 631-6 (2004).

(3) Bernard Laumon et al, ≥Cannabis Intoxication and fatal road crashes in France: population based case-control study,≤ British Medical Journal doi:10.1136/bmj.38648.617986.1F, Dec. 2, 2005.

(4)  Franjo Grotenhermen et al., ≥Developing Science-Based Per Se Limits for Driving under the Influence of Cannabis: Findings and Recommendations by an Expert Panel,≤ (International Association for Cannabis Medicine, 2005) posted at

NORML Questions Tactics Behind Feds Latest
Drugged Driving Campaign*

Organization Reiterates Stance Against Driving While Impaired By Cannabis

*Washington, DC: Recent allegations by the White House Office of National Drug Control Policy (ONDCP) that cannabis is a significant causal factor in on-road accidents and may adversely impact psychomotor skills up to 24 hours after past use are not supported by scientific evidence, said NORML Executive Director Allen St. Pierre.*

His remarks were in response to a White_House_Campaign launched earlier this week, entitled Steer Clear of Pot.

*While acute cannabis intoxication has been shown to have demonstrable impact on psychomotor performance, these effects are typically mild and short-lived lasting at most one to three hours, and certainly not 24 hours, as claimed by the ONDCP. Moreover, unlike with alcohol, the accident risk caused by cannabis particularly among those who are not acutely intoxicated is often limited because subjects under its influence are generally aware of their impairment and compensate to some extent, such as by slowing down and by focusing their attention when they know a response will be required. This response is the opposite of that exhibited by drivers under the influence of alcohol, who tend to drive in a more risky manner proportional to their intoxication.*

According to an analysis of on-road crashes released in September by an international expert panel: The most meaningful recent culpability studies indicate that drivers with THC concentrations in whole blood of less than 5 ng/ml have a crash risk no higher than that of drug-free users. THC blood levels typically fall below 5 ng/ml in recreational cannabis users within 60 to 90 minutes after inhalation.

*Nevertheless, St. Pierre reaffirmed NORMLs_Stance that operating a motor vehicle under the influence of any controlled substance is unacceptable. Responsible cannabis consumers never operate a motor vehicle in an impaired condition, regardless of whether that impairment is due to alcohol, cannabis or some other intoxicant or prescription medication, he said. Public safety demands not only that impaired drivers be taken off the road, but that better objective measures of impairment be developed to more accurately identify drivers under the influence of drugs.*

For more information, please contact either Allen St. Pierre, NORML Executive Director, or Paul Armentano, NORML Senior Policy Analyst, at (202) 483-5500. A comprehensive review of cannabis impact on driving appears in NORMLs report, You Are Going Directly to Jail: DUID Legislation: What It Means, Whos Behind It, and Strategies to Prevent It, available online at:

NORML Questions Tactics Behind Feds Latest Drugged Driving Campaign
cannabisnews November 30, 2005

*Ganja & Driving

NORMLs Weekly News Bulletin September 29, 2005*
Positive Marijuana Result Not Associated With Auto Crash Culpability
September 29, 2005 Baltimore, MD, USA
*Marijuana use, as indicated by the presence of cannabis metabolites, is not associated with crash culpability among injured drivers, according to data presented at the annual conference of the Association for the Advancement of Automotive Medicine.*
Read More

Paranoid Pot Smokers Drive More Carefully

Alcohol Impairs Driving More Than Marijuana

Cannabis May Make You a Safer Driver

U.S. Department of Transportation, National Highway Traffic Safety Administration
(DOT HS 808 078), Final Report, November 1993:
*THCs adverse effects on driving performance appear relatively small*

Cannabisnews Search Cannabis & Driving

Cannabis & Driving

*While it is widely accepted that cannabis use can slow motor skills and reduce task-attention, increasing in severity with dose, research has shown that cannabis use is less likely to dangerously impair driving abilities than alcohol at similar levels of intoxication. Cannabis intoxication often makes smokers more aware of their impairment, causing them to slow down and become more cautious while also worsening reaction time and attention. Cannabis users often report that driving speeds are experientially faster than normal: driving a given speed feels faster and more dangerous than the same speed does while sober.*

There have been a number of studies which have looked at this issue and most have found that cannabis smoking does degrade driving performance. There is a little contradictory evidence about whether cannabis in combination with alcohol causes worse impairment than alcohol alone, but so far the data heavily favors the view that the combination substantially increases risks over either alone.

*The research so far does not provide a clear answer to how much risk of accidents increase with moderate levels of cannabis intoxication, but only confirms that the risks of cannabis-alone impairment are lower than those of alcohol-alone impairment. The following are a collection of summaries & papers which look at the issue of cannabis & driving performance.*

*Executive Summary of Driving Impairment Effects of Alcohol & Cannabis* (1994)

The influence of cannabis on driving

UK Lords Report On Cannabis & Driving

Alcohol impairs driving more than marijuana  New Scientist March 2002

*As someone who spent 35 years wearing a police uniform, Ive come to believe that hundreds of thousands of law-enforcement officers commit felony perjury every year testifying about drug arrests.*
Joseph McNamara, former San Jose Chief of Police

The Joseph McNamara Collection

Pot Less Harmful Than Alcohol or Tobacco

Cannabisnews Search alcohol
Alcohol impairs driving more than marijuana

*A single glass of wine will impair your driving more than smoking a joint. And under certain test conditions, the complex way alcohol and cannabis combine to affect driving behaviour suggests that someone who has taken both may drive less recklessly than a person who is simply drunk.*
New Scientist March 2002

Marijuana Myth: Marijuana Is A Major Cause Of Highway Accidents

*The White House Office of National Drug Control Policy (ONDCP) and certain Wisconsin legislators have launched a new crusade against drugged driving, with a heavy emphasis on marijuana. This crusade is largely based on scientific misinformation, and it could lead to the enactment of bad laws.*

*US National Highway Traffic Safety Administration Reports*

Marijuana And Actual Driving Performance

Marijuana Use And Driving
by Robbe 1994

Marijuana And Actual Driving Performance
by Robbe, NHTSA, 1999

Marijuana & Alcohol Combined Increase Impairment
NHTSA 1999

*Drivers under the influence of marijuana retain insight in their performance and will compensate where they can, for example, by slowing down or increasing effort. As a consequence, THCs adverse effects on driving performance appear relatively small.*
Robbe, NHTSA 1993

Cannabis Campaigners Guide to Cannabis & Driving

Schaffer Library References on Drugs and Driving

Cannabis And Road Safety:  An Outline Of The Research Studies To Examine The Effects Of Cannabis On Driving Skills And On Actual Driving Performance

*Professor Hall considers cannabiss contribution to danger on the roads to be very small; in his view the major effect of cannabis use on driving may be in amplifying the impairments caused by alcohol.*
UK Lords Report, 1998

DUI Law & Cannabis

WhiteHouses Steer Clear of Pot Campaign  (2003)

Crancer Study, Washington Department of Motor Vehicles
*Simulated driving scores for subjects experiencing a normal social high and
the same subjects under control conditions are not significantly different. However,
there are significantly more errors for alcohol intoxicated than for control subjects*

The Cost Of Alcohol!

Antidrug Ad Blitz Criticized For Omitting Alcohol!

*ONDCP has several slick television commercials on the subject. One shows dramatic auto accidents and two crash test dummies passing a joint while a serious voice says, In a recent study, one in three reckless drivers tested positive for marijuana. Note the careful phrasing. The idea is to make viewers think that marijuana caused the reckless driving, without really saying that it did.*

Cannabis/Driving Studies Australia: No Proof Cannabis Put Drivers At Risk  (2001)

UK: Cannabis May Make You A Safer Driver  (2000)

Australia: Cannabis Crash Risk Less: Study  (1998)

Australia: Study Goes to Pot  (1998)

Marijuana Not A Factor In Driving  University Of Toronto Study (1999)

*We didnt choose to fight this drug war, it chose us.
Now we have to do whatever it takes to fight this evil and change this system.
No more shattered lives!*
Chris Conrad, author Shattered Lives

Marijuana Not a Factor in Driving Accidents
March 29, 1999
*The safety hazards of smoking marijuana and driving are overrated, says U of T researcher Alison Smiley.
Recent research into impairment and traffic accident reports from several countries shows that marijuana taken alone in moderate amounts does not significantly increase a drivers risk of causing an accident unlike alcohol, says Smiley, an adjunct professor in the department of mechanical and industrial engineering . While smoking marijuana does impair driving ability, it does not share alcohols effect on judgment. Drivers on marijuana remain aware of their impairment, prompting them to slow down and drive more cautiously to compensate, she says.*

Despite studies and common sense

harsh anti-pot driving laws are becoming commonplace.

Vigilante narcs are out for blood

Government spies, fences and vigilantes on their way

Performance testing provides a valid alternative to zero tolerance drugged driving tests.

*Corruptisma repulica, plurimae leges.
(The more corrupt a republic, the more laws.)*
Tacitus, Annals III 27

Two decades of research show that marijuana use may actually reduce driver accidents.

Government agencies block med-pot studies

UK cops are testing for drugged drivers despite studies which show stoners drive safely.

Ontario lawyer driving high, organizing rallies and fighting corruption. 

*The American Medical Association knows of no evidence that marihuana is a dangerous drug.*
Dr. William Woodward of the American Medical Association, in hearings on the 1921 Marihuana Tax Act

Science shows pot makes safer drivers

Common marijuana myths disspelled, with sources

Regular medicinal pot user safe to drive while under the influence

It Was Not the Drug, but the Criminalisation

Setting Drug Impairment Levels Far Off

No Increased Risk for cannabis/driving

*We can have justice whenever those who have not been injured by injustice
are as outraged by it as those who have been.*
Solon (594 B.C.)

DUI, Drunk Driving Arrest Consequences

*DUI-DWI Convictions Can Happen to Anyone, Even Our Leaders*
By age 40, about 20% of all males in the USA have received a DUI conviction. Of course, some men have received MORE than their allotted share, such as Vice President Richard (Dick) Cheney. Here are copies of President Bush’s 1976 DUI in Maine, followed by Cheney’s DUI records of two back-to-back DUIs in Wyoming.

*Canada Would Ban Bush — But There Are Loopholes* By Rebecca Cooper (ABC News)

W A S H I N G T O N, Nov. 3 — Even if George W. Bush is elected president, he may need special permission to get into Canada because of his arrest for drunken driving.

Dick Cheneys Youthful Indiscretions

Bush Jr.s Skeleton Closet

Convicted of drunk driving. Lied repeatedly to cover up his arrest.

*Faced with the biggest crisis of his political life, President Bush has hit the bottle again, The National Enquirer can reveal. Bush, who said he quit drinking the morning after his 40th birthday, has started boozing amid the Katrina catastrophe. Family sources have told how the 59-year-old president was caught by First Lady Laura downing a shot of booze at their family ranch in Crawford, Texas, when he learned of the hurricane disaster.*

 Bushwhacked: Jenna Bushs drinking incident
*The presidents twin daughters have been caught trying to buy beer using fake ID. But, asks Katie Roiphe, whats all the fuss about? Theyre just teenagers bringing a touch of colour to the White House* Deceptions

DOT HS 808 078 Marijuana and Actual Driving Performance
*Final Report, Nov. 1993 Conclusions on page 108 of the copy I received from the NHTSA are interesting and informative. A sample : It is possible to safely study the effects of marijuana on driving on highways or city streets in the presence of other traffic. Drivers under the influence of marijuana tend to over-estimate the adverse effects of the drug on their driving ability and compensate when they can; e.g. by increasing effort to accomplish the task, increasing headway or slowing down, or a combination of these.*

DOT HS 808 939 Marijuana, Alcohol and Actual Driving Performance July 1999 Conclusion on page 39 midway of paragraph 5.1 of the copy I received: The addition of the new data, (for marijuana), broadens the range of reactions that may be expected to occur in real life. This range has not been shown to extend into the area that can rightfully be regarded as dangerous or an obviously unacceptable threat to public safety. DOT HS 809 020 Visual Search and Urban City Driving under the Influence of Marijuana and Alcohol March 2000: Conclusion 1 on page 24 of the copy I received. Low doses of marijuana taken alone, did not impair city driving performance and did not diminish visual search frequency for traffic at intersections in this study.

*General Discussion on page 22 . Previous on-the-road studies have also demonstrated that subjects are generally aware of the impairing properties of THC and try to compensate for the drugs impairing properties by driving more carefully (Hansteen et al, 1976; Casswell, 1979; Peck et al, 1986; Robbe 1994)*.

DOT HS 809 642 State of Knowledge of Drug Impaired Driving Sept 2003: Experimental Research of Cannabis, page 41 midway: The extensive studies by Robbe and OHanlon (1993), revealed that under the influence of Marijuana, drivers are aware of their impairment, and when experimental tasks allow it, they tend to actually decrease speed, avoid passing other cars, and reduce other risk-taking behaviors.

*DOT HS 808 065 The Incidence and Role of Drugs in Fatally Injured Drivers Oct. 1992 In discussing the Distribution of Ratings on Driver Responsibility Table 5.12 page 64 of the copy I received, paragraph (p.65); Responsibility, drugs and alcohol, third paragraph, the following appears: Note that the responsibility rates of the THC-only and Cocaine-only groups are actually lower than that of the drugfree drivers. Although these results too are inconclusive, they give no suggestion of impairment in the two groups. The low responsibility rate for THC was reminiscent of that found in young males by Williams and colleagues (1986).” This study is remarkable in its propensity to attack itself as inconclusive.*

Forensic Science Review Vol. 14, Number One/Two, Jan 2002, surely must be the reference of note regarding metabolic functions and where the THC goes following ingestion. This review discuses THC and its metabolites; THCCOOH, 11-OH-THC to mention the most discussed. Location and type of measured quantities of these and other metabolites should be easy to use to determine if a driver is stoned or was stoned yesterday, or last week. Mention was made of a man who had measurable levels of metabolites sixty-seven days after ingesting Cannabis.

*Chap IX paragraph D, Summary appears to be of two minds. While stating: Studies examining Cannabis causal effect through responsibility analysis have more frequently indicated that THC alone did not increase accident risk … it continues optimistically suggesting that further exhaustive research may rebut that. All of the studies agree that combining Cannabis with any other drug, such as Alcohol a major deleterious effect on driving skills, as is benzoates with Cannabis … it rapidly becomes evident that Cannabis in combination with any number of other drugs is not to be desired, but that Cannabis and Cocaine alone in all six studies have the smallest perceived safety risk of all the drugs and drug combinations tested and against drug-free drivers.*

Sacramental Cannabis Food, Fuel, Fiber, FARMaceuticals, Hardrug&Booze AlterNative!