The science behind roadside THC testing and diving into Sask.’s zero-tolerance policy

Click to play video: 'The science behind roadside THC testing and diving into SGI’s zero-tolerance policy'
The science behind roadside THC testing and diving into SGI’s zero-tolerance policy
WATCH: Some cannabis users in Saskatchewan have been concerned about possibly testing positive if pulled over by police while driving and given a roadside drug test, even though they're not impaired. Global's Emily-May Simmonds breaks down the science. – May 10, 2024

Some cannabis users in Saskatchewan have been concerned about possibly testing positive if pulled over by police while driving and given a roadside drug test, even though they’re not impaired.

People have been voicing their concerns online when it comes to the province’s policies around cannabis use and driving, many claiming it’s somewhat of a grey area.

Global News did a deep dive into the science around the roadside drug tests used by law enforcement and how THC can be detected in the body, and clarified SGI’s zero-tolerance policy around cannabis use and driving.

SGI spoke about cannabis use and driving in previous coverage around the topic, suggesting that Global News should also reach out to police to speak on it more.

Roadside oral swab tests

The Regina Police Service and Saskatoon Police Service didn’t have anyone to speak on the matter, but a video posted by Saskatoon police showed how the oral swab tests work.

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The video notes that an officer needs reasonable suspicion to believe that a person has a drug in their system to demand the test. Refusing that demand is a criminal code offence.

The oral swab test doesn’t show a quantitative measurement, just whether someone is over the limit or not.

The video also addresses concerns for people using cannabis medicinally, stressing that officers need reasonable suspicion to administer the oral swab test.

“Using medicinal marijuana is no different than using any other kind of medicine. If you’re prescribed codeine or any other kind of opiate, you have to abide by that particular medicine’s directives,” the video said.

It also addressed the question of how long people should wait after using cannabis before driving, saying there are several variables at play and that if someone is unsure, they should speak with a physician.

“The most important thing is not to guess and risk it.”

Global News’ Emily-May Simmonds reached out to RCMP last week to speak on the matter and offer some clarification, but was directed to the RCMP’s website and given a statement.

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“The RCMP’s message to anyone who consumes an intoxicant (whether legal or illegal) is ‘impaired is impaired.’ Individuals shouldn’t drive after drinking alcohol, taking prescription drugs that can impair or consuming cannabis or any other substance that could impair their ability to operate a motor vehicle,” RCMP said.

The RCMP’s website said even if an oral fluid sample comes back negative, an officer can demand further testing through a Standardized Field Sobriety Test if they see indications of drug use.

If a person fails that test, they could be arrested and put through the 12-step Drug Recognition Expert evaluation.

One of the test kits commonly used by law enforcement is Draeger’s DrugTest 5000, which tests for both cocaine and THC.

A Draeger representative said the device detects delta-9-tetrahydrocannibol, which is the active analyte in THC that causes impairment.

The testing devices are looking for a specific limit of 25 nanograms, which is the per se limit in oral fluid in Canada.

It was noted that the tests do not pick up metabolites, which Draeger explained are the products of the degradation of THC that can stay within a person’s system for days and possibly weeks.

Draeger boasted that the DrugTest 5000 is the most accurate and reliable roadside test on the market, pointing to a study done by the United States Department of Transportation that said the test was 98.7 per cent accurate for THC and 99.1 per cent accurate for cocaine.

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It was noted that the devices were put against evaluation standards laid out by Canada’s minister of justice and the attorney general of Canada.

Draeger said while it strives to be as accurate as possible, 100 per cent accuracy isn’t possible, however, more goes into an investigation to determine if someone is impaired.

When Global News reached out to the province’s Ministry of Justice about the regulations around cannabis use and driving, we were referred back to SGI.

The zero-tolerance policy

Tyler McMurchy, spokesperson for SGI, said there are consequences for getting caught with cannabis in your system while driving.

“The vast majority of people running afoul of provincial or federal legislation are being suspended provincially, and there is no $1,000 fine for that,” McMurchy said.

He said there are still financial consequences for exceeding provincial limits: people will have their licence suspended and vehicle impounded and will have to take a course, depending on whether this is a first, second or third offence.

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McMurchy addressed comments seen online that this is a cash grab for SGI, saying when it comes to impaired driving, there’s no profit for anyone.

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He clarified that “zero tolerance doesn’t mean you can’t have anything in your system whatsoever.”

He said the oral swab tests used by police are calibrated to look for recent use.

“There is somewhat of a threshold there.”

He said police who have administered the test have told him that the THC will clear out of people’s saliva within 12-24 hours.

McMurchy recognized that there is a lot of fear among daily users of cannabis, but said due to all the variables that need to be taken into consideration when using cannabis, he can’t guarantee that people will pass a test if demanded by an officer.

Mark Brayford, a local defence lawyer, said last week that tests for THC don’t necessarily gauge impairment.

He said there isn’t a close correlation between the level of THC in a person’s bloodstream and their level of impairment.

“With respect to the science about THC levels in a person’s bloodstream, the reality is if you’re going to be a daily user of cannabis, you’re not legally going to be able to drive your automobile. It’s that simple,” Brayford said.

Brayford gave an example of someone smoking cannabis every evening. He said that even if you are not actually impaired by cannabis the next morning, you might not be able to legally drive.

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“Is it a real possibility that you have more THC than is legally allowed, even though you’re not impaired? Yes, it is.”

Bill C-46, which was passed in June 2018, established laws and penalties around driving under the influence of cannabis, which created three new offences to the Criminal Code of Canada:

  • driving with two nanograms (ng) but less than 5 ng of THC per millilitre (ml) of blood
  • driving with 5 ng or more of THC per ml of blood.
  • driving with a combination of 50 milligrams (mg) of alcohol (or more) plus 2.5 ng or more of THC per millilitre of blood
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He said there is a debate that has been ongoing with regard to whether the levels set in Bill C-46 are catching people who are innocent of any wrongdoing.

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Brayford gave an example of a case out of Ontario in 2022 called R. v. Robertson where a judge did an extensive review of whether it should be unconstitutional to have a law where the mathematical level could be a criminal offence for the accused even though that person is not impaired.

“She looked at both sides of the equation and said, ‘Yes, there are people who are going to get caught by the five-nanogram level who aren’t impaired, and they’re going to get a criminal record and all the consequences of a criminal charge.'”

He said the judge questioned whether that should be constitutionally possible, and ultimately came to the conclusion that the law could stand.

Brayford said that’s not the end of the debate, however, saying that at some point the Supreme Court of Canada will be the final decision on this question.

“That’s a debate that will probably rage for the next 10 years.”

Research and science behind THC testing and impairment

Robert Laprairie, associate professor at USask and director of education for the Canadian Consortium for the Investigators of Cannabinoids, said how long cannabis stays in a person’s system depends on how they use it.

He said THC levels peak quickly if you smoke cannabis, usually within 15 minutes, and fall gradually over time, having roughly about 95 per cent of that THC out of your system within 24 hours.

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Laprairie said peak levels take a lot longer if you consume cannabis by eating it in the form of a gummy, saying it can take up to three hours to reach peak levels.

“You might see residual levels of THC in the blood up to 24 hours or even 36 hours later, and all of this is highly variable,” Laprairie said.

He couldn’t speak on the oral swab test, but described the federal blood test limits of two ng and five ng as a “very low and very sensitive limit of detection.”

He said you wouldn’t see a large disparity between how much THC shows up in your saliva compared with your blood.

Laprairie said “impairment” is a very subjective thing and couldn’t speak on the legal ramifications of what constitutes impairment.

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He spoke about people who use cannabis frequently, saying there are some studies that say THC can get partitioned and stored in fatty tissue.

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“There is a chance, although the data I would say is still growing at this point, that some of those THC molecules are being stored.”

Laprairie likened the federal government’s two-ng testing limit to a near zero-tolerance policy.

“It’s a very low limit, and it’s done to be as safe and conservative as possible.”

He said in his own research, he’d seen slightly higher levels before he’d consider it impairment, but he understood the safety implications behind the federal limit.

Laprairie said cannabis is still pretty new when it comes to legalization and expected further growing pains when it comes to managing it.

“Hopefully these issues get solved or worked out in the next two to three years.”

He said there are people actively looking into driving policy law when it comes to cannabis use, pointing to labs in Australia looking into the matter.

Laprairie said there are some medications people can use in Canada besides cannabis that have THC in them.

“Those drugs would be impairing and intoxicating in the same way cannabis would be. The chemical that is causing that high is still there.”

He said cannabis also has a multitude of uses besides recreational use and can help with sleep, anxiety, fear, depression, pain or symptoms of disorders like multiple sclerosis.

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Laprairie would like to see the government support more research around cannabis, adding that more research could look at how it interacts with other drugs and how it affects people’s behaviours on a broader scale.

Global News reached out to the federal government for an interview and received a statement and a link to the government of Canada’s website.

“Before introducing legislation to better address cannabis-impaired driving, which became law in 2018, the government received scientific advice on drug-impaired driving from the Drugs and Driving Committee (DDC) of the Canadian Society of Forensic Science. The prohibited blood drug concentration (BDC) levels, including those for THC, are based, in part, on the DDC’s final report on Drug Per Se limits outlining considerations and recommendations for enacting criminal offences for driving over a prohibited BDC,” the government said.

The feds said law enforcement has been training officers to test for impairment and that the Standardized Field Sobriety Test and the 12-step Drug Recognition Expert evaluation can add further evidence to support a drug impairment charge.

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