The Casual Cannabis Use War Rages On: The Challenges of Inconclusive and Conflicting Medical Evidence

Employers will continue to face challenges in the workplace arising from the legalization of cannabis use. The recent case of BC Rapid Transit Company v. CUPE Local 7000 highlights the complex tensions between employee privacy and public safety, as well as the difficulties employers can have in managing cases where employees exercise their right to use cannabis.

This part of the saga involved an interim application by CUPE to suspend an order of the Chief Medical Officer (CMO) that the grievor be required to engage in monitoring, including random drug testing and counselling for a year. There were safety issues which weighed in favour of the order but conclusive medical evidence was a difficulty.


The employee/grievor is a SkyTrain Attendant (STA) involved in operations such as customer service, fare inspection, limited mechanical or electrical fault correction and emergency-response. STAs are trained and required to assume manual control and operation of SkyTrain vehicles in emergency situations. In other words, they drive a train when needed. As a result, the STA position is a “Safety Critical Position.”

SkyTrain is a “railway” and is subject to various railway-related legislation. Regulations require STAs over the age of 40 to undergo a health assessment every three years. The grievor provided a urine sample that indicated the presence of cannabis metabolites. He had also answered no to the question of marijuana use.

The Employer’s Policy prohibits employees from reporting to work unfit for duty. They must not consume alcohol or drugs (except authorized medications) while on duty. However, off-duty use of marijuana is not prohibited.

CMO and Testing Process

Under regulated Medical Rules, a CMO determines whether an employee in a Safety Critical Position is medically fit for duty. The CMO is not an employee of Rapid Transit. The CMO decided the STA should be removed from his duties pending confirmation of the result. The STA was given a second examination by another physician, at which time, the grievor admitted he used marijuana three to four times a week. The grievor explained he had not originally admitted marijuana use because he “felt that it was not the employer's concern if he used marijuana outside of working hours."

The second physician reported that the grievor did not meet the diagnostic criteria for marijuana dependence (DSM-IV-TR) or marijuana use disorder (DSM-5); however, in the presence of continued marijuana consumption, the grievor had a disproportionately elevated “occupational risk diagnostic profile” which precluded engagement in the duties of an STA. The physician was of the view that the grievor was not fit to return to work until he was shown to be negative for marijuana through biological chain of custody testing; given his lack of honesty in concealing marijuana use and his continued use despite the consequences, he should be monitored for one year with randomized urine drug screen testing. The physician concluded that despite finding a “Low Probability of Substance Use Disorder”, there was cause for concern due to the continued consumption of marijuana 3-4 times weekly, particularly given the impact on his ability to do his job as a SkyTrain attendant. Further, a second test at the time the grievor saw the second physician indicated continued cannabis use.

Taking a conservative approach to the medical information, including continued cannabis use, given the importance of public safety, the CMO determined a year of randomized testing was necessary.

Arbitral Decision

The Union sought an interim order suspending the drug testing.

In considering whether to grant an interim order, the Arbitrator considered the privacy issues inherent in random drug testing and whether a breach can be adequately compensated in damages and found that if the employer’s policy was found to violate the collective agreement, the law provides for the payment of money damages to employees whose privacy has been wrongly infringed by random testing. However, the Arbitrator determined that the testing regime was highly intrusive to the grievor, controlling his daily routine with call-in obligations and demanding he give bodily fluids twice per month, making things like arranging a vacation very challenging.

Ultimately, the Arbitrator determined the CMO had made the decision to require testing on the basis of medical evidence which did not provide a diagnosis but a “suspicion of a diagnosis” where testing showed “the possibility of a mild Substance Use Disorder, substance misuse or a developing problem.” The Union had also submitted a medical opinion critical of the physician, including on questions of the length of cannabis impairment and the lack of an evidentiary basis for some conclusions. In that context, the Arbitrator characterized the intrusiveness as irreparable, and determined the grievor had an arguable case as to whether the testing decision was justified which required a full hearing. The Arbitrator noted the grievor took counselling, remained abstinent, complied with the monitoring agreement, and the CMO’s safety plan has been substantially completed. Thus, he found the balance of convenience favoured suspending testing because it would now be “reasonably safe to uphold the grievors privacy and dignity.”

Further Thoughts

Some have said this case pits the right to smoke pot recreationally against transit safety. Others may go farther and say the right to recreational cannabis use prevailed because the Arbitrator ordered suspension of drug testing. This particular battle was about one employee who had failed a drug test. It turned on its own facts and left the question of the drug testing regime to another day.

This case demonstrates the significant challenge employers have in obtaining clear and conclusive evidence on these issues. It is not uncommon for employees to demonstrate suspicious behaviour and medical indicia which may suggest a disorder but are not conclusive. Further, the science on impairment is scant and evolving. What should employers do when faced with this uncertainty? In this case, the CMO erred on the side of public safety. The decision, however, raised the risk the grievor could claim damages for breach of privacy. That is a risk most employers will choose to take.

  • Ryan  Berger

    Ryan Berger is a leading privacy and employment lawyer, with a primary focus on providing strategic advice to businesses and employers.

    Ryan leads the firm’s Privacy Group and routinely advises public and private sector ...

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Lawson Lundell's Labour and Employment Law Blog provides updates on the most recent legal developments impacting the Canadian workplace and offers practical tips for employers. We cover a range of topics, including labour relations, employment law, collective bargaining, human rights, employment standards, employment equity, workers' compensation, business immigration, privacy, occupational health and safety and pensions and employee benefits. 

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