With Legalization Looming, Police Face Challenges Measuring Cannabis Impairment

In the following months, police forces across Canada may no longer need to crack down on the casual marijuana user, but they are expecting a drain on their resources due to the anticipated uptick of intoxicated drivers. Will municipal police forces across Canada be prepared, come October 17th, when the nation welcomes in an era of recreational cannabis?

Already, data suggests 32 percent of drivers treated after a motor vehicle accident testing positive for marijuana, and in one survey, nearly 10 percent of those surveyed reported smoking cannabis before getting behind the wheel. The Canadian federal government is not taking the issue lightly, as it recently passed legislation allowing for roadside oral saliva tests, and has committed $161 million to train police, purchase equipment, and launch a public awareness campaign.

However, despite the federal push for roadside testing, experts in the field question the effectiveness of the approved testing methods. Regional police forces are also hesitant to implement any of the available marijuana intoxication tests and invest in unproven equipment. According to Inspector Murray from the Ottawa Police Service, the force will continue to monitor the progress of roadside testing and await the results from some of the cases currently working their way through the court system.  

With the ongoing debate on the legality and effectiveness of roadside testing for marijuana intoxication, it’s hard to predict what the future might hold. Will police forces adapt oral saliva or breathalyzer style tests, or will the courts take issue with the validity and legality of these methods?

The Underlying Issues Related to Marijuana Intoxication

The scientific literature draws many conflicting conclusions about marijuana intoxication and the possibility that any single roadside test can determine impairment.  Unlike alcohol consumption, impairment from most other intoxicants hinges on many unpredictable factors, including age, tolerance, sex, weight, disease management, and interaction with other drugs. Presence of active ingredient in saliva, blood, or urine, is no indication of impairment level.

According to Kevin A Sabet, in his recent book Contemporary Health issues on Marijuana, the basic premise of intoxication based on blood levels is “simply impossible to apply to other drugs, including marijuana, because there is no stable relationship between impairment level and blood or other tissue levels.” He unceremoniously concludes that pursuit of finding an applicable threshold for all adults is a “fool’s errand.”

Oral swabs, such as the devices approved for use across Canada, face very similar questions about their effectiveness on predicting impairment. The current body of research does not support a one size fits all approach to determining marijuana intoxication.

Current Technologies In Roadside Testing

To date, there are three methods pursued in roadside environments for determining impairment from cannabis, including blood testing, oral saliva swabs, and breathalyzers (which are only in the trial period thus far).

Law enforcement prefers blood tests (in some circumstances) based on their accuracy for determining cannabis use, but they still cannot measure impairment. On top of this, law enforcement must obtain a warrant, and the suspect must be taken into custody before the test can get underway. They are notably challenging to execute, and often delayed long after the arrest. While they may accurately measure drug levels, they are not always applicable for a roadside stop.

As mentioned, the Canadian government recently approved the use of roadside saliva tests, which are already undergoing trial use by some police forces in Michigan, California, among others. German-based Dräger secured the approval of the Canadian government in August, for their Dräger Drugtest 5000 oral drug testing system. They are easy to use, comparatively affordable, but haven't yet demonstrated effectiveness.

Recent studies, performed in Norway on the Dräger Drugtest 5000 found it ineffective in colder temperatures with a high return of false positives.  Although now available for regional police forces to use in Canada, many are hesitant to invest without more information on accuracy, as is the case with the Ottawa police force.

Finally, there are some companies currently investigating breathalyzers for marijuana, including Alcohol Countermeasure System and Hound Labs. These devices are a long way from implementation among law enforcement agencies, but will presumably offer another portable and simple-to-use device for roadside testing. However, little data exists on their reliability and accuracy. As with oral swabs, similar questions circle marijuana breathalyzers. Can data from a cannabis breathalyzer really determine impairment; moreover, will it hold up in court?

It is impossible to determine if and when technologies will accurately measure cannabis impairment based on a threshold level of active THC. Most police forces across Canada are instead investing resources into innovative police training, aimed to give police the tools to identify intoxicated drivers without devices.

Specially trained officers in California put suspects through a 12-step test, monitoring their accuracy, concentration, and vital signs, to make a sobriety decision. When October 17th hits in Canada, its these human-driven tests which may be the most reliable and accurate tool police have in their tool belt.