Employers warned: zero tolerance drug policies may violate human rights

A recent Ontario arbitration decision involving employees who disclosed medical cannabis use should put employers across Canada on notice about the legal risks of applying zero tolerance drug policies – even in safety-sensitive workplaces.

The ruling highlights the importance of balancing workplace safety obligations with the legal duty to accommodate workers with disabilities – particularly when those workers are authorized to use medical cannabis.

The case involved two employees with safety-sensitive jobs who were removed from their roles after disclosing they used medically prescribed cannabis to manage serious health conditions.

“The decision really emphasizes why it’s so important not to ever have zero tolerance policies,” says Sheryl Johnson, partner at Sullivan Mahoney LLP in Niagara Falls.

“At the end of the day, you have to take every person individually under the code, in order to ensure that an employer meets their obligation to accommodate.”

Zero tolerance and individual circumstances

One of the grievors had Crohn’s disease and used medical cannabis to manage pain, anxiety, and sleep disturbances. Although his use followed medical guidance and was not linked to any impairment at work, the employer required him to be drug tested. They then asked him to sign a "last chance" agreement before being reinstated to his job, which he refused.

This broad application of a zero tolerance policy – intended originally to limit off-duty recreational cannabis use—meant that the employer failed to assess whether the employee could safely perform his duties while using the medication. The arbitrator ultimately found that the company failed in its duty to accommodate and awarded him $10,000 in human rights damages, plus full back pay and benefits.

While Johnson says she recognizes the need for employers to maintain health and safety standards for employees, and in this case the public, she says broad-strokes policies can expose well-meaning employers to discrimination claims.

“If you have a zero tolerance policy that just prescribes what the outcome is or what the penalty needs to be, when there's also human rights elements and the duty to accommodate as part of it, then it's not going to be proportional, and it's not going to be considering what the individual circumstances are, and it becomes very unfair and discriminatory," she says.

“It also leads to a lack of flexibility and nuances with regards to individual circumstances, which, when you're dealing with a Human Rights Code, is always a requirement. It doesn't allow you to consider mitigating circumstances.”

Testing for marijuana, cannabis impairment

Mathias Link, partner at Fasken in Toronto, explains that the context of safety-sensitive work complicates how policies must be drafted and enforced.

“Employers are obligated to provide their employees with a safe workplace,” he says, citing occupational health and safety legislation, "and that means they must be fit both physically and cognitively, to work and they must be able to work safely.”

A major challenge for employers, however, lies in the science of testing cannabis impairment. While breathalyzers can reliably link alcohol levels to impairment, cannabis testing is far less clear.

“It’s not like alcohol where with a breathalyzer, [testing] the level of alcohol in your blood, if it coincides with impairment, you're able to demonstrate that. With marijuana, it’s different because it remains in the fatty tissues for months,” Link says.

“So you could have someone who is a chronic recreational marijuana user who could be taking marijuana even the day before work, and they might still be able to function … [the test] doesn’t necessarily demonstrate impairment, but what you can prove is recency of use.”

Difficulty assessing THC impairment

That scientific uncertainty makes it difficult to rely on test results as evidence of safety risk in the workplace. Yet the employer's policy triggered disciplinary measures based on cannabis presence, without assessing actual impairment or context.

“Blood concentration levels of THC do not accurately measure the amount of cannabis consumed or, more importantly, an individual’s likely impairment,” the decision detailed.

“Nor do THC concentrations predict individual impairment. The inability to readily and accurately measure impairment, whether using blood concentration levels, oral fluid levels, or behavioural tests complicates the issue of cannabis use in relation to persons who perform safety-sensitive work. Like alcohol use, impairment is variable as among individuals and dependent on a variety of factors. However, testing for impairment is less certain in relation to cannabis use than for alcohol use.”

Zero tolerance drug policies and proportional discipline

The decision underscores that when workplace policies enforce automatic penalties for drug use, regardless of context or other mitigating factors such as disability, they risk being found unreasonable or discriminatory.

“[Zero tolerance policies] can result in harsh and unjust punishments,” Johnson says. "We always talk in employment and labour law: Does the penalty fit the crime? Is it proportionate?”

Such rigid policies also “don’t allow you to consider mitigating circumstances,” she says, including medical conditions, mental health concerns, or treatment plans.

In unionized environments, applying zero tolerance policies without nuance can severely compromise an employer’s ability to uphold just cause for termination, Johnson explains.

In this decision, this became clear when the arbitrator found that the penalty imposed on certain employees was disproportionate and failed to consider individual circumstances – ultimately undermining the employer’s position.

“In labour law, you have to have just cause to terminate someone,” Johnson says, adding that unlike non-unionized employment, where no-cause terminations can usually proceed with severance or notice, unionized settings are a different matter, requiring progressive discipline and evidence of a fair process.

That requirement means employers must walk a thin line between policy enforcement and fairness – and in union environments, harsh penalties without progressive discipline are rarely upheld.

“If you're giving them a penalty that is the maximum before termination, then arbitrators are always going to walk that back, because there was no progressive discipline to get you to the point where you're going to have just cause for the discipline,” Johnson says.

“Arbitrators do not like harsh consequences that don't fit what the misconduct was.”

Duty to accommodate with zero tolerance

Canadian employers have a legal obligation under human rights legislation to explore accommodation options before taking adverse employment actions, especially when disabilities are involved.

“In any situation where you have a duty to accommodate and it’s a safety-sensitive position, you have to have a policy—but you also have to apply it appropriately to the circumstances,” Johnson says.

“That's part of where the employer stepped into the quicksand in this situation, is that they said it was only for recreational use, and then they applied it also in relation to medical use.”

Instead of investigating whether the employee could still perform his duties safely or whether alternative roles were suitable, the employer focused only on the fact of cannabis use, she says.

“They just said, ‘You've had cannabis, you can't perform any job' … and they didn't look at anything other than the fact that they had a zero tolerance policy.”

Increases in medical marijuana use since legalization

Link agrees that policy matters must be clearly defined but also applied in context.

Employers should be even more careful now that recreational marijuana use is legalized, he says, but reminds them that employees have responsibilities, too.

“It's an area of challenge even before recreational marijuana was legalized, but the reality is, with the legalization of recreational marijuana, I think the use of marijuana for medical reasons has also increased, and that presents a challenge for employers... because they have a duty on the one hand under human rights legislation, to consider with an employee who has a medical condition that marijuana is an option … Can that be done, and can it be done safely? And maybe it can't be done safely.”

Effective drug and alcohol policies must walk a legal and ethical tightrope between safety and individual rights.

“It’s always a balancing between safety and human rights,” says Johnson. “But one doesn’t trump the other. They both have to work together.”

Disclosure and collaboration with drug policies

Another best practice is to ensure employees understand their disclosure obligations before issues arise; Link explains that a well-drafted policy must cover this: “If you are taking any type of drug that could impair your ability to work safely, you have an obligation to disclose it to the employer, who will then talk to you about it and make inquiries and determine whether or not it impacts your ability to work.”

Employers have legitimate reasons for erring on the side of caution, Johnson says, which is why some rely on zero-tolerance policies that can cause more complication and costly arbitration processes.

“The whole idea with regards to accommodation is to be collaborative and to have discussions and to disclose information and look at different options,” she says.

“Because whether it's a court, an arbitrator, the Human Rights Tribunal, they're all going to look to see what you did to discharge your duty to accommodate. And so it's always a balancing between safety and human rights, but one doesn't trump the other. They both have to work together. And so, safety is very important, but so are someone's human rights.”