Is Marijuana Use Safe Or Not? And What If The Answer Is Not Clear?

A recent arbitration decision from Newfoundland offers a possible lifeline for employers faced with the possibility of having to accommodate medical cannabis users in safety sensitive workplaces. In Lower Churchill Transmission Construction Employers’ Association v. IBEW, Local 1620, Arbitrator Roil dismissed a grievance challenging a refusal to hire on the basis that there would be undue hardship to the employer due to the inadequacy of existing drug testing technology to determine impairment caused by cannabis use.

The grievor was authorized to use “medical cannabis”, which he vapourized and inhaled. He was authorized to consume approximately 1.5 grams of cannabis with a high THC potency every evening. The grievor applied for 2 general labourer positions, which were both determined to be safety-sensitive. The grievor was not accepted for either position because of his admitted “medical” cannabis use. The employer took the position that the grievor’s use of cannabis created a risk of impairment which was not acceptable for someone in a safety sensitive role.

The grievor’s physician gave evidence that 4 hours after ingestion, the grievor would be capable of working in a safety-sensitive position. The employer challenged this evidence and led evidence supporting its concerns about residual impairment of the grievor. Contrary to the opinion of the grievor’s physician, Health Canada and the College of Physicians and Surgeons of Newfoundland and Labrador had previously issued professional advice that, due to the long half-life of THC, impairment could last up to 24 hours after use. Furthermore, the arbitrator concluded that the grievor’s general practitioner was not an expert on the subject at hand.

The arbitrator concluded that, if safety risk is to be managed, the employer needs to be able to measure the impact of the “medical cannabis” on the performance of the worker. The evidence supported a general lack of effective or practical means to accurately test impairment in the workplace from evening cannabis use. The arbitrator concluded that remedial or monitoring processes would not help in offsetting this safety risk. As such, it was determined that accommodating the grievor would be an undue hardship for the employer. Without sufficient means for impairment testing, the employer was not required to compromise safety and assume the risk associated with cannabis impairment.

This is an important case for employers. Due to the complexity of the drug, it is generally accepted that current testing technology is unable to accurately measure impairment from cannabis use. It is also generally accepted by most physicians that THC impairs. However, not all “medical marijuana” contains high levels of THC. Some has less than 1% THC while it is high in CBD (another chemical that is not impairing and tends to counter the effects of THC). In this case, the arbitrator accepted that in respect of this grievor, the lack of reliable testing for impairment was a safety concern that the employer should not have to bear. That is of course a conclusion based on the medical evidence presented in the specific case but it is hard to question the overall logic of its reasoning.

If an employee is ingesting cannabinoids (whether authorized or after legalization), employers should attempt to ascertain usage, dosage, potency and obtain expert evaluation of safety to work. At least two Alberta arbitrators have determined that use of authorized cannabinoids is not necessarily inconsistent with work in a safety sensitive position. One critical factor is the relative concentration of THC versus CBD. The individual’s circumstances have to be evaluated. The case will hinge on the particular expert evidence presented in the particular case. However, this case now provides a sensible answer to the question: what if there is a doubt? As one would hope, safety comes first in weighing the competing factors.