When Canada’s anti-prohibition contingent decided to put together a recreational marijuana bill, in order to appease those concerned that the move would not result in an increase in highway fatalities, lawmakers made sure to include a very strict DUI code. And, sure enough, Bill C-46, which passed in June, includes a massive overhaul of Canada’s impaired driving laws.

However, in order to enforce that code, a reliable roadside test is needed to detect the use of cannabis. So, the country spent millions researching their options. An independent committee made up of toxicologists and traffic safety experts was put together to research available tools and make a recommendation.

A number of options were tested in a National Research Council laboratory and evaluated by the Canadian Society of Forensic Science. In addition, Public Safety Canada and the RCMP initiated a study on oral fluid screening devices and concluded they were “a useful additional tool for Canadian law enforcement.”

A decision has finally been reached. Canada’s Justice Department, headed by Attorney General Jody Wilson-Raybould, is set to give its blessing to the Draeger DrugTest 5000 roadside saliva test. The device, which is produced by a company based in Germany, is already being used in the United Kingdom and Germany. (The Draeger device was not one of the two used in the RCMP study.)

The test involves swabbing a driver’s mouth to collect oral fluids to test for the presence of THC, the main psychoactive ingredient in cannabis. A positive result on the roadside test gives police reasonable grounds to detain the driver and require further testing, i.e. a blood test. The results of the blood test will then be examined by a drug recognition expert to make a final determination as to whether or not to press charges for DUI.

Unfortunately, the law calls for “per se” limits for drug blood levels. What this means is that police can file criminal charges against a driver based solely on the level of THC in the blood with no actual proof of impairment.

According to a report in Canada’s National Post, the federal government is budgeting $81 million for provinces and territories to buy the screening devices and to train officers in their use.

Why This Is a Dumb Idea

While tests for measuring alcohol blood levels have proven to be at least mostly reliable, there’s really no such thing as a reliable test for impairment due to consumption of cannabis. Although roadside tests and blood tests may be able to determine that a driver is a cannabis consumer, they cannot be used to prove impairment.

In a story on CBC.com, reporter Laura Glowacki points out some of the flaws in this system. She quotes Scott Newman, a spokesperson for the Criminal Defense Lawyers Association of Manitoba, Canada, who says “There’s no true, reliable way to test for the presence or absence of recent drug consumption… The saliva test doesn’t really tell you a lot because the effects of marijuana can stay in the system of anyone up to 30 days.”

If you’re an occasional user, saliva tests can detect THC for about 24 hours after consumption, and, depending on a variety of common factors (such as how often one brushes their teeth and which toothpaste they use) this can stretch to as long as 72 hours. And, if you were a heavy smoker but recently quit, saliva tests can produce a positive result for weeks after the last joint has been smoked. Even 24 hours is surely a sufficient passage of time for any impairment from THC to have worn off.

Furthermore, research has proven that other compounds found in cannabis, particularly CBD, can greatly reduce the effects of THC, while others, such as a terpene known as myrcene, can greatly increase impairment. Theoretically, in order for a test to be even somewhat credible, it would have to test for CBD as well.

Let’s say a cannabis user has consumed 10 milligrams of THC over the past 24 hours, but has also consumed 100 milligrams of CBD. The level of impairment in this case would be impossible to predict. It would depend on factors which are outside of the realm of drug testing, including the expression of CB1 cannabinoid receptors in certain areas of the individual’s brain. It’s just not going to happen.

Aside from there being no perfect measure of impairment from cannabis use, the tests are easy to beat. Chemicals known as adulterants can be used to reduce THC levels in the saliva. For example, hydrogen peroxide is just one of many adulterants that can be used to quickly skew results. It would be fairly easy for a driver to keep one of these products handy in case of getting pulled over.

Also, according to Alfonzo Porter at leafbuyer.com, “There are more important considerations when it comes to the ability to tell whether you’re a pothead. You have to take into account your body mass, your level of physical activity, age, metabolic rate, overall health, the level of your individual drug tolerance, the potency of the weed strain, and how much of it you smoked.”

The reliability of THC tests is likely to be challenged in court by defence lawyers who will easily poke holes in the results no matter which test is being used. Police in many U.S. states already use saliva testing and, according to Scott Newman, they rarely result in impaired driving convictions.

After spending millions of dollars on research, Canada has decided to go with the venerable roadside saliva test to determine driver impairment due to consumption of cannabis. Another C$81 million is budgeted for purchasing and training. The problem is, saliva tests — or any other drug tests for that matter — don’t really correlate to impairment.

After spending millions of dollars on research, Canada has decided to go with the venerable roadside saliva test to determine driver impairment due to consumption of cannabis. Another C$81 million is budgeted for purchasing and training. The problem is, saliva tests — or any other drug tests for that matter — don’t really correlate to impairment. #canada #cannabis #marijuana #dui


This article by Cannabiz News editor Rick Schettino originally appeared on PotNetwork.com.