Cannabis use in the workplace has been the subject of much debate since medical cannabis was legalized. While the use of recreational cannabis and its effects on the workplace seem to dominate the current conversation, a recent decision from the Newfoundland and Labrador Superior Court (“Court”) confirmed that employers do not necessarily have an automatic obligation to accommodate medical cannabis use in safety sensitive workplaces if undue hardship can be established.

In Lower Churchill Transmission Construction Employers’ Association representing Valard Construction v. IBEW Local 1620, a unionized employee, Mr. Tizzard (the “Grievor”), had a prescription to consume medical marijuana. He reported he consumed it in the evenings after work hours, and felt no impairment in the morning when he reported to work. Supporting this evidence, the Greivor’s physician advised him not to drive or operate machinery for four (4) hours after inhalation and six (6) hours after ingestion, but that she did not believe the “level of impairment remaining the next day would affect his job performance.”

However, the Arbitrator did not accept the Grievor or his physician’s evidence. Instead, he found that impairment can last up to 24 hours, and there are currently no readily available testing resources to allow an employer to adequately and accurately measure impairment arising from cannabis use on regular basis. The Arbitrator determined, and the Court agreed, that the inability to measure residual impairment of cannabis constituted undue hardship in a safety sensitive workplace.

In dismissing the Greivor’s application for judicial review, the Court held:

…that the Arbitrator accurately identified the issue before him in this case as a question of the Employer’s duty to accommodate use of medical cannabis by a worker in a safety sensitive position. He found that the duty to accommodate did not extend to a requirement that the Employer accept a risk resulting from the possibility of impairment. He concluded that the evidence of possible impairment adduced by the Employer (and not contradicted by the Grievor’s treating physician who conceded the possibility of residual impairment beyond the initial four hours from use) met its onus to demonstrate undue hardship which displaced its acknowledged duty to accommodate.

The law on the use of cannabis in the workplace and the implications of off-duty use of cannabis on the workplace continues to develop. Employers are well advised to seek advice when dealing with specific issues as each case must be looked at independently.


Bill 66, Restoring Ontario’s Competitiveness Act, 2019, has now received royal assent. It implements changes the Employment Standards Act, 2000, in the following ways:

A provincially regulated Employer in Ontario will no longer need to:
(1) post the ESA poster in the workplace;
(2) have Director approval to make agreements to work more than 48 hours a week; and
(3) have Director approval to make agreements allowing employees to average hours of work over a maximum of 4 weeks for determining overtime entitlements.

As well, the Court of Appeal overturned a lower court decision that had created a new and independent tort of Harassment in Ontario (Merrifield v. Canada (Attorney General) 2017 ONSC 1333). In making this decision, the Court of Appeal stated amongst other things, that a plaintiff can see sufficient redress through the current damages for infliction of mental distress and/or through the Human Rights Tribunal.