Ontario arbitrator upholds discharge for refusing post-incident drug and alcohol testing

Can an employee be terminated for refusing a post-incident drug and alcohol test?

Yes. In Dome Mine Ltd. and USW, Local 7980, 2026 CanLII 78264 (ON LA), an Ontario arbitrator upheld the termination of an employee who refused a valid post-incident drug and alcohol test. The decision reinforces that where an employer has a legitimate basis to require testing, an employee’s refusal to comply may itself justify termination, even where the underlying safety breach may have other explanations.

The decision is particularly relevant for employers operating in safety-sensitive workplaces, highlighting the importance of clear testing policies, prompt action following serious incidents, and consistent documentation supporting testing decisions.

What happened in Dome Mine?

The grievor was a heavy equipment operator at Dome’s mine. On January 19, 2026, the grievor and a co-worker were assigned safety-sensitive work. Before work could begin, the area was required to be fully locked out.

Both employees knew that lockout procedures had to be followed, but they entered the area and worked for approximately three hours without a proper lockout in place. No one was injured, but the incident was treated as a serious “near miss.”

Management decided that the circumstances triggered post-incident drug and alcohol testing under its policy. The co-worker complied and tested positive. The grievor refused. He maintained that there was no “probable cause” for testing and later used profane language in discussions with HR. He was terminated on January 28, 2026, for refusing to undergo testing.

The union grieved the discharge. It argued that the employer had overreacted, had not conducted an adequate investigation before ordering testing, had applied the policy inconsistently, and had failed to account for inadequate lockout training.

Why did the arbitrator uphold the discharge?

The Arbitrator found that the post-incident testing threshold was met.

The grievor was directly involved in a serious lockout violation in a mining environment, and management was entitled to move quickly to determine whether fitness for duty concerns relating to alcohol and drug use may have contributed. The Arbitrator rejected the union’s submission that the employer first had to complete a broader investigation into other possible causes, such as training gaps or operational conditions at the mine.

The Arbitrator also dismissed the argument that the employer had been inconsistent because similar or more serious safety violations in the past had not led to testing. In particular, an employer’s prior failures do not prevent it from taking reasonable safety precautions in a later case, especially in a high-risk environment.

Further, the Arbitrator accepted that the grievor’s understanding of the mill lockout process was weak and that the employer’s training may not have been ideal, however, that does not render the termination unreasonable.

The grievor was not terminated for committing the lockout violation itself; he was terminated for refusing a valid order to undergo testing. In the Arbitrator’s view, any shortcomings in lockout training were not a defence to insubordination in that context.

Lastly, the Arbitrator held that discharge was an appropriate penalty in this case. Even though the grievor had lengthy service and a clean disciplinary record, the Arbitrator accepted the employer’s legitimate concern that reducing the penalty could encourage employees in future cases to refuse valid testing orders, particularly where they suspected they might test positive. That deterrence rationale weighed in favour of upholding termination.

Practical takeaways for employers

Overall, Dome Mine underscores that in hazardous workplaces, arbitrators may give substantial weight to employer safety obligations and may view refusal to submit to valid post-incident testing as misconduct serious enough to justify discharge. Some practical tips for consideration going forward are below:

• Ensure testing policies are clearly drafted and regularly communicated. Employers in safety-sensitive settings should have express post-incident testing language that explains when testing may be ordered;
• Act quickly, but document the basis for testing. The decision confirms that employers do not need proof of actual impairment before ordering testing after a significant incident, but they should still record the facts linking the employee to the event;
• Training deficiencies may not excuse refusal to comply with testing policy. Even where underlying safety training is imperfect, refusing a valid testing order may still support termination; and
• Prioritize current safety obligations, not past practice. Past inconsistent enforcement may be relevant to discipline arguments, but it will not necessarily defeat an otherwise justified testing decision.