When does misconduct become just cause for dismissal?

Just cause is not a list of firing offences. It is decided by a contextual proportionality analysis, and it is a high, fact-specific bar. The leading authority is the Supreme Court of Canada’s decision in McKinley v. BC Tel, which asks whether the nature and degree of the misconduct, weighed against all the surrounding circumstances, justifies dismissal. As Monkhouse Law summarizes the holding, the test requires proportionality: the punishment must be proportional to the misconduct in the context of the entire employment relationship. The core question is whether the conduct caused a breakdown in the relationship such that it could no longer viably subsist. Iacobucci J. grounded the approach in the principle of proportionality.

That framework has a sharp consequence: no category of conduct is automatic cause. McKinley expressly overruled the older line holding that any dishonesty justifies dismissal, stating that a single act of dishonesty as a matter of law no longer gives an employer an absolute right to dismiss its employee. Even significant dishonesty has to be assessed contextually against the employee’s position and record. The same goes for insubordination, absenteeism, conflict of interest, and the rest. A single incident justifies dismissal only if the misconduct is serious enough to cause the irreparable breakdown of the relationship. Treating theft, insubordination, or dishonesty as automatically meaning cause is the classic, expensive error.

This is where the paper trail pays off. The culminating-incident or cumulative-cause doctrine lets an employer rely on a properly documented prior record so that a final, possibly minor, last-straw incident supports dismissal, but only where the earlier incidents were documented and the employee was warned. In Daley v. Depco International Inc., an employee disciplined over nine separate incidents, none individually sufficient, was found to have built up, in Echlin J.’s phrase, enough bricks to constitute a just cause wall, because the file was well documented and the notices referenced prior warnings. Chopra v. Easy Plastic Containers Ltd. quoted that same image and, adopting a contextual and proportional approach, found the incidents taken together were not minor or trifling. The same logic is long-settled in unionized arbitration: the employer must have warned the employee that prior misconduct was unacceptable and that more could lead to dismissal, and without a culminating incident that itself justifies discipline, an employee cannot be dismissed on their work record alone.

Timing matters just as much as documentation. If an employer knows of misconduct and fails to act within a reasonable time, it may be taken to have condoned it and lose the right to rely on it. The principle traces back to McIntyre v. Hockin in 1889 and was confirmed in Chambers v. Omni Insurance Brokers, where the Court of Appeal held that condonation is subject to an implied condition of future good conduct, so previously condoned offences can be put back in the scale when new misconduct occurs. An employer is entitled to a reasonable time to investigate and consider its position, but an unexplained delay generally signals condonation.

Finally, there is no “near cause” in Canada. There is no partial-cause doctrine that trims the notice period for misconduct falling short of just cause. In Dowling v. Halifax (City), the Supreme Court refused to accept any near-cause argument and ended the debate: an employer either has cause or it does not, with no middle ground. The statutory notice and severance framework, and any dollar figures, belong to the compliance and numbers clusters. This note is general information, not legal advice.

For an Ontario SMB, the practical reading is that cause is harder to prove than it feels in the moment and almost never automatic. Document as you go, act promptly once you know, and do not assume a single dramatic incident clears the bar on its own. And keep in mind the separate question handled in the next note: even a valid just-cause finding does not necessarily wipe out statutory termination pay.