There are some easy-to-follow rules regarding how long to wait after consuming cannabis before driving. I was given them the first day I got my prescription for medical cannabis almost a decade ago. I was recently given the same instructions by Mothers Against Drunk Driving: wait four hours after smoking and eight hours after eating cannabis.

Just do that and you’ll avoid actually breaking the drugged driving laws, I was told.

But with legalization looming, our federal lawmakers continue to adhere to outdated and faulty science as it relates to roadside drug testing.

Although there have been numerous recent studies that state THC does not break down in the body in a similar fashion to alcohol, our laws continue to operate as if that is exactly the case.

The Dräger DrugTest 5000 recently became the first oral-swab saliva test for roadside use by police officers approved by the Department of Justice.

The feds claim that only marijuana consumed within the last six hours will be detected, but several more recent and variable-controlled studies of oral-swab tests can show impairment levels in regular or medicinal users even if they have abstained for long periods of time before driving, which concerns constitutional lawyer Jack Lloyd.

“They’ve created these per se limits that will effectively mean a great number of people can never drive,” he says.

“This law is supposed to protect us from impaired drivers,” Lloyd continues, “[but] it’s not protecting us from impaired drivers – it’s just giving police a blanket authority to charge random Canadians.”

The idea that only recently consumed marijuana would cause THC to be seen on such tests has been called into question by newer studies that have corrected for a study-altering variable that previous studies didn’t take into consideration – namely, how regular or medicinal users break down THC in the body as opposed to those who do not regularly consume marijuana.

A 2014 study out of Norway found that THC was showing up in the tests of regular marijuana users even after they had abstained for days or weeks.

“These results suggest that the toxicokinetics of THC are not as simple as was previously thought,” the study says. “This makes interpretation of toxicology results much more difficult than it has been when it was assumed that THC followed a well-defined pattern of elimination kinetics and further suggests that a reliable algorithm for mathematical modelling of THC metabolism in real-world heavy users remains elusive.”

The government of Canada has also concluded that THC levels are poorly correlated with impairment in a massive study concerning blood-drug regulations last year.

“It should be noted that THC is a more complex molecule than alcohol, and the science is unable to provide general guidance to drivers about how much cannabis can be consumed before it is unsafe to drive or before the proposed levels would be exceeded,” the study states.

Yet federal lawmakers continue to move forward.

Why is our government doing this? Because it’s easier to pretend we have a way of determining marijuana inebriation in the same way we do for alcohol. It’s easier to quell the concerns of the anti-marijuana lobby by claiming to have a way of catching marijuana-impaired drivers than it is to admit that we don’t.

Marijuana legalization meant many potential voters could turn against the federal government. Taking a strong stance against marijuana-impaired driving helps to quell those concerns and prevent marijuana-grumpy voters from supporting another party.

That not a single U.S. state or country that has legalized marijuana has seen a rise in traffic accidents suggests our law-and-order response is to a perceived problem, not an actual one.

This isn’t to say people should drive under the influence of marijuana. Far from it.

But if you’re a regular or medicinal user, there is a more than 50 per cent chance you will fail the oral-swab test regardless of how long you have abstained, causing life-altering effects.

If this happens to you, legal experts agree that it’s a good idea to keep your mouth shut. Do not debate with the officer as to when the last time you consumed was and do not make a sarcastic comment you feel is too funny to pass up. Just ask for a lawyer and panic quietly inside.

If you fail the test, your car will be impounded and you’ll be off to the police station for further testing and scrutiny.

The good news is that the oral-swab saliva test is not the smoking gun the police need to convict you. The bad news is that the other tests conducted by drug-recognition evaluators (DRE) are just as problematic.

A blood test will be also be administered. Here, too, recent tests have shown THC in blood is just as irrelevant to impairment as in saliva. But if you’re a regular user, you’ll likely fail this test, too.

The combination of blood and saliva tests along with a DRE’s testimony could be enough to land you a DUI conviction despite you never having driven a car while impaired.

As legalization moves forward, there will be lawyers and activists working to help those whose lives are unfairly affected by new driving laws. How long this will take, or even if it will be successful, is unclear.

Concerned citizens might consider contacting their MP to ask for clarity on the laws. You could even send your MP this article. I won’t mind.

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