CCPartners | Blog

Second Positive Drug Test Justified Termination for Cause: Ontario Court Reinforces Safety-Sensitive Workplace Policies

For management-side employment lawyers, successful just cause decisions can sometimes feel like spotting a 4-leaf clover. They exist—but they're uncommon.

Ontario courts continue to remind employers that dismissal for cause is reserved for the most serious misconduct. Policy breaches and poor judgment alone rarely justify the workplace equivalent of the death penalty.

The recent Ontario Superior Court decision in McCarthy v. Bison Transport Inc. is a welcome reminder that cause remains available where employers have a clear policy, consistently enforce it, and carefully consider their human rights obligations before terminating employment—it has little to do with luck!

The Facts

The employee worked as a long-haul truck driver for Bison Transport, a safety-sensitive position involving cross-border transportation throughout Canada and the United States.

Like many transportation employers, Bison maintained a comprehensive Drug and Alcohol Policy. Drivers received training, signed acknowledgements confirming their understanding of the policy, and were advised that violations could result in discipline up to and including termination.

In 2014, the employee failed a random drug test after testing positive for THC.

Rather than dismissing him, Bison referred him to a substance abuse professional, required him to complete education and return-to-work requirements, and reinstated him after professionals concluded that he did not suffer from substance dependence. He also received a written warning advising that another failed test could result in termination.

Three years later, he failed a second random drug test.

When asked to explain the result, the employee admitted to recreational marijuana use, denied having an addiction, and did not seek accommodation. Following its investigation, Bison terminated his employment for cause.

The employee sued for wrongful dismissal, human rights damages, aggravated and punitive damages, and unpaid overtime. The Court dismissed every aspect of his claim.

Why the Employer Succeeded

Unlike many recent wrongful dismissal decisions, McCarthy was not a case where the employer relied on a zero-tolerance policy without considering the surrounding circumstances.

Instead, the Court carefully applied the contextual approach to just cause and concluded that several factors supported dismissal:

• the employee worked in a genuinely safety-sensitive position;
• he was fully aware of the employer's Drug and Alcohol Policy;
• he had previously violated the same policy;
• he had already been given a second chance;
• he understood another violation could result in dismissal; and
• there was no evidence that he suffered from a disability requiring accommodation.

Taken together, the Court concluded that the employment relationship had been irreparably damaged and that dismissal for cause was proportionate.

Human Rights Obligations Still Matter

One of the most important aspects of the decision is what didn't happen.

After the first failed drug test, Bison referred the employee for a professional assessment. The assessment concluded he did not suffer from addiction.

Following the second failed test, the employer again gave him an opportunity to explain the circumstances and determine whether accommodation obligations were engaged. Once again, there was no evidence of dependency or disability. During the litigation, the employee ultimately abandoned his disability claim altogether.

The Court had little difficulty concluding that Ontario’s Human Rights Code protects disabilities—not recreational drug use.

For employers, this distinction is critical. A positive drug test does not automatically establish a disability, but employers should also avoid assuming that no accommodation is required. Each case must be assessed on its own facts before discipline is imposed.

Good Policies Are Only Half the Battle

The decision also highlights an often-overlooked reality: having a well-written policy is not enough.

Bison succeeded because it consistently followed its own process. It trained employees, obtained written acknowledgements, enforced the policy uniformly, investigated before making a decision, and documented each step along the way.

Too often, employers undermine otherwise excellent policies by applying them inconsistently or making termination decisions before gathering the relevant facts.

As McCarthy demonstrates, consistency is often what transforms a good policy into a successful defence.

A Quick Word on the Overtime Claim

The employee also claimed more than $230,000 in unpaid overtime based largely on his own reconstruction of driving hours using mileage records and estimated average speeds.

The Court rejected the claim, finding both that significant portions were barred by the applicable limitation period and that the employee's calculations were fundamentally unreliable.

While secondary to the dismissal issue, the decision serves as a useful reminder that employees bear the burden of proving their damages with reliable evidence—not creative math.

Employer Takeaways

Review your policies. Drug and alcohol policies should be clear, regularly updated, and appropriate for the workplace, particularly where employees occupy safety-sensitive positions.

Document everything. Signed acknowledgements, written warnings, and documented investigations were all important pieces of Bison's successful defence.

Investigate before terminating. Employers should always consider whether a failed drug or alcohol test may engage human rights obligations before imposing discipline.

Be consistent. Courts are far more likely to uphold discipline where employers consistently apply their policies and treat similar situations alike.

Final Thoughts

Cause remains one of the most difficult standards for employers to establish.

McCarthy does not change that.

What it does provide is a practical roadmap for employers operating in safety-sensitive workplaces. Bison had a reasonable policy, communicated it clearly, gave the employee a second chance, considered accommodation, and only terminated employment after the employee repeated the same misconduct.

Sometimes employers ask whether giving an employee a second chance weakens their position if misconduct happens again.

This decision suggests the opposite.

Handled properly, a second chance—paired with a clear warning and consistent enforcement—may be exactly what persuades a court that enough really is enough.

If you are contemplating discipline, dealing with substance use or abuse in the workplace or have questions about accommodation, the team at CCP is always ready to assist.

Click HERE to access CCPartners’ “Lawyers for Employers” podcasts on important workplace issues and developments in labour and employment law.