Accommodating Medical Marijuana Use in Safety-Sensitive Positions May be an “Undue Hardship” for Employers

The inability for employers to measure impairment from cannabis is proving to have an effect in the workplace.  In a recent case, an Arbitrator ruled in favor of the employer for not placing a worker who uses medical cannabis on a project in a safety sensitive position.

The Arbitrator concluded:

“The Employer did not place the Grievor in employment at the Project because of the Grievor’s authorized use of medical cannabis as directed by his physician. This use created a risk of the Grievor’s impairment on the jobsite. The Employer was unable to readily measure impairment from cannabis, based on currently available technology and resources. Consequently, the inability to measure and manage that risk of harm constitutes undue hardship for the Employer.”

In this case, the Grievor’s physician advised that the affects of the medical cannabis would only cause impairment for four hours following his use (which occurred in the evening).  However, information from Health Canada states that impairment can last for up to 24 hours following use.  Because of the lack of ability to test for impairment, in a safety sensitive position, the employer could not guarantee that the employee would not be impaired on the job.

“The Arbitrator was satisfied that THC is known to effect judgment and motor skills, and that THC can, and does, cause impairment. The Arbitrator cited Health Canada’s advice to healthcare professionals that depending on the dose, impairment from THC can last more than 24 hours after last use due to the long half-life of THC.”

This is a very specific situation and is dependent on the job being “safety-sensitive” (as determined by the Arbitrator).  As a result, “The arbitrator’s recognition of residual impairment for up to 24 hours from medical cannabis use allowed a finding of undue hardship.”

This is a significant case, and it is still to be determined if there will be an appeal.  Regardless, this shines an interesting light on the use of medical marijuana in the workplace, and is a good reminder for employers that safety is still priority number one.  There is still significant work to be done in the areas of measuring/recognizing/confirming impairment, and with the upcoming legalization of recreational cannabis, the need is even greater.


Case: Lower Churchill Transmission Construction Employers’ Association and IBEW, Local 1620
Accommodating medicinal marijuana: Recent arbitration case highlights challenges for employers (Canadian HR Reporter)  May 8, 2018
Canada: Medical Marijuana Found To Be Undue Hardship In Safety Sensitive Positions – The Problem Of Residual Impairment (Mondaq) May 2, 2018

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