The sale and use of edible cannabis is legal in Canada as of October 17, 2019, but in the year since cannabis legalization, the issue of workplace impairment remains unresolved.

Medical and recreational consumers continue to face uncertainty on whether use will lead to termination, while employers grapple with duties to accommodate, crafting effective drug policies and identifying impairment without reliable tests. Legalization may increase the number of long-term users so employers must consider impairment under such conditions and also to what extent they will account for emerging medical evidence that cannabis may not be as impairing as originally thought.[1] Some safety-sensitive companies are adopting zero tolerance policies,[2] but as social standards change and evolve, and as more Canadians eat, drink and smoke cannabis, employers must craft impairment tests and policies that reflect changes in our understanding of cannabis’ effects.

The article will look at a 2019 Newfoundland and Labrador Superior Court decision involving workplace cannabis testing to illustrate the ongoing impairment issue. It will then look at an app-based test for impairment as a possible solution to current concerns and finishes with a discussion on new studies showing that medical users of cannabis may actually perform better if permitted to consume.

Testing for Workplace Impairment Remains Fraught with Challenges

It is difficult to prove an employee was impaired by cannabis because there is no infallible test for it. The Ontario Human Rights Commission says that while breathalyser tests for alcohol are accurate measures of consumption and impairment, they are not so for other drugs. Past use may be detected but not the amount of drug used or whether that equates to impairment at the time of testing, and while blood tests are more accurate, they are highly intrusive. Many employers, therefore, will argue a worker’s breach of an agreed to drug and alcohol policy or, in the case of medical cannabis, undue hardship where accommodation is in issue.

The reasons in Valard discuss both these points in the absence of any evidence of the worker’s actual impairment.[3] The worker there had suffered disabling chronic pain for years and turned to medical cannabis as a last resort. When he was dismissed from a previous job, where his use was not an issue, his union helped him to find other work. The possible roles were safety-sensitive and required clear drug and alcohol tests as a condition for employment. The worker was open about his use, and when he was denied both roles because of it, brought a grievance based on the employers’ failure to meet their duty to accommodate his disability.

The court upheld the arbitrator’s decision dismissing the grievance noting that employers cannot manage the risk of impairment without an accurate measure of it—accommodating cannabis-consuming workers is an undue hardship in safety-sensitive workplaces. Despite the absence of any evidence the worker was or would be impaired by his medically prescribed use, it was a risk resulting from the possibility of impairment that amounted to an undue hardship.[4]

This, the court determined, shifted the onus from employer to the worker now obligated to produce medical evidence that the job could be performed safely.[5] Justice Boone considered this a reasonable approach, especially in light of the fact that the worker’s hiring was contingent upon passing a drug test, which he could not. Any other possibility of employment required reasonable accommodation, an impossibility owing to the lack of tests available for impairment.

Such rulings clearly favour employers who are absolved of developing meaningful tests for impairment, and they affirm that the mere possibility of impairment in safety-sensitive workplaces allows dismissal or refusal to hire, not actual impairment. Conversely, employers are obligated to provide safe workplaces for all employees; the use of cannabis, medicinal or recreational, compromises their ability to do so.

Coming to a Mobile Device Near You: is App-Based Impairment Testing the Answer?

Current methods rely on a combination of observation and testing to conclude a worker is impaired but Canadian law severely restricts when the latter is permissible. Accidents and near misses are well-settled exceptions.[6] Such tests can be taken with saliva, urine or hair but only show previous consumption, not that the worker was impaired at the time of the relevant incident. Whatever the test’s outcome, observing symptoms like fatigue, distraction, poor coordination and glassy eyes can further help identify impaired workers or build a case in the instance of arbitration over dismissal.

Reacting to incidents, however, is not ideal and so showing actual impairment before an accident occurs is preferred. If random testing is not permitted, then identifying impairment must be the goal. Canadians have already heard about the limitations of the Drager Drug Test 5000. Developed and used in Europe, it allows for saliva tests and has been used by Canadian police to detect impaired driving. This test, however, has shown differing levels of accuracy—sometimes with up to a 14% error rating—and questions remain as to its effectiveness under Canada’s climate conditions.[7] Breathalyzer tests are also being developed with varying success.

A new app called Druid aims to overcome these problems by testing for overall impairment, rather than simply for drug use. It claims to be effective for drugs and alcohol but also concussion, cognitive decline in seniors, military fitness and the effects of fatigue. It does so by first recording a baseline of the individual when unimpaired and then measuring future performance against it. It uses video-game-like testing and measures cognitive and behavioural impairment. Applications like Druid  may overcome existing legal limits on random drug testing imposed by case law and human rights legislation by going right to the heart of the matter—impairment—rather than using drug use as its proxy, an approach that risks discrimination and thereby infringing an employee’s human rights.

Emerging issues

As more workers consume cannabis—especially those who will eat it—issues will emerge. What are the present and residual effects of edibles? Do long-term users suffer impairment from withdrawal? Do current standards require revision and what of the possibility that for some, cannabis use may improve their ability to work?

On this last point, anecdotal accounts, and now research, suggest that cannabis consumption can improve performance rather than impair it. Numerous studies detail its negative effects, but some reviews report such evidence as mixed and contested.[8] Others are compiling evidence of the beneficial cognitive effects of cannabis. A 2018 research study published in Frontiers in Pharmacology and conducted by Harvard Medical School Affiliate Staci Gruber, PhD, suggests medical cannabis treatment for various conditions shows brain activation patterns similar to those exhibited by healthy persons.[9] Medical cannabis normalizes brain function and patients report improvement in their clinical status and health-related measures as well as decreased use of prescription medication like opioids and benzodiazepines after three months of treatment.

An important point made was that recreational and medicinal users experience differing effects on performance with recreational users showing decreased task performance. The report concludes that this may be due in part to medical consumers using different types of cannabis, for example, strains with higher CBD, which is likely to impact cognitive function. Changes may also be due to the secondary effects of cannabis use including a reduction in clinical symptoms, improved sleep and decreased use of conventional medicines. These observations support an argument that, for medical consumers of cannabis, there is a real risk that existing arbitral and workplace standards unfairly penalize them, especially as they take steps to overcome medical conditions that are likely already impacting work performance.

In the case of the worker in Valard, the denial of work opportunities because of his chronic pain management was a straightforward but limiting one. Without accounting for the type of cannabis he consumed, or a measure of his alleged impairment compared to a baseline performance, the employer may have denied work to an otherwise healthy worker who had arrived at an effective pain management plan.

The number of users amongst workers can only increase with legalisation and workplaces risk alienating competent employees by imposing zero-tolerance policies or refusing to adopt more nuanced assessments of impairment. While a proven test for impairment is currently unavailable, emerging products may resolve this. In the meantime, employers can more actively manage their workers’ consumption by creating a more considerate and proactive management and assessment policy with more frequent reviews to account for the rapidly developing medical literature on the issue.

[1] Gruber SA, “The Grass Might Be Greener: Medical Marijuana Patients Exhibit Altered Brain Activity and Improved Executive Function after 3 Months of Treatment,” Frontiers in Pharmacology (January 17, 2018).

[2] Zero tolerance refers to demands that workers test below a certain very low threshold of THC in their bodies.

[3] International Brotherhood of Electrical Workers, Local 1620 v. Lower Churchill Transmission Constructions Employer’s Association Inc. and Valard Construction LP, 2019 NLSC 48 (Valard) on appeal from International Brotherhood of Electrical Workers, Local Union 1620 v Lower Churchill Transmission Construction Employers' Association Inc., 2017 CanLII 59779.

[4] A fact uncontradicted by the Grievor’s treating physician who conceded the possibility of residual impairment.

[5] Valard at para 34.

[6] Communications, Energy and Paperworkers Union of Canada, Local 30 v. Irving Pulp & Paper, Ltd., 2013 SCC 34 is perhaps the most important case on the topic of workplace testing.

[7] Hallvard Gjerde et al, “Evaluation of Drager DrugTest 5000 in a Naturalistic Setting,” Journal of Analytical Toxicology, 42:4 (February 2, 2018).

[8] Broyd SJ et al, “Acute and Chronic Effects on Cannabinoids on Human Cognition – A Systematic Review,” Biological Psychiatry (April 1, 2016); Shrivastava A et al, “Cannabis and cognitive dysfunction,” Indian Journal of Psychiatry (Jul-Sep 2011).

[9] Gruber SA, “The Grass Might Be Greener: Medical Marijuana Patients Exhibit Altered Brain Activity and Improved Executive Function after 3 Months of Treatment,” Frontiers in Pharmacology (January 17, 2018).