Case snapshot
At a glance
- Case
- Can a Municipality Be Convicted Under Ontario's OHSA Without Due Diligence?
- Court / Tribunal
- Ontario Superior Court of Justice
- Citation
- 2026 ONSC 3671 ↗
- Date
- July 10, 2026
- Area of law
- Immigration Law
- Key issue
- Whether a municipality charged under the Occupational Health and Safety Act can escape conviction by proving it took all reasonable steps to prevent a workplace hazard it had no knowledge of.
- Outcome
- The Superior Court allowed the appeal, set aside the convictions, and entered acquittals after finding the municipality had established due diligence on both counts.
- Why it matters
- This decision clarifies that Ontario employers and municipalities cannot be held liable under the OHSA for hazards they could not reasonably have discovered, even when a worker is harmed.
Legal principle
The rule from this case
Under the Occupational Health and Safety Act, charges against an employer are strict liability offences — meaning the Crown does not have to prove the employer intended to break the law. However, an employer can avoid conviction by proving, on a balance of probabilities, that it took all reasonable care in the circumstances to prevent the violation. This is called the due diligence defence. The court confirmed that due diligence is not a perfect-hindsight standard. An employer is judged on what it knew, or reasonably ought to have known, at the time — not on what investigators later discover. Where a hazard is genuinely latent and hidden (such as an underground vault that does not appear in any accessible records and is not visible during a reasonable site inspection), a court cannot simply assume that more steps were available without pointing to actual evidence of what those steps were and whether they were feasible.
Important limits
What this does not mean
This decision does not mean that employers or municipalities can ignore workplace safety obligations and then claim ignorance after the fact. The due diligence defence requires proof of a genuine, active effort to identify and address hazards — records searches, site inspections, engagement with the constructor, and other reasonable precautions appropriate to the circumstances. The ruling also does not change the basic framework of OHSA liability. The municipality in this case conceded that the prohibited act (actus reus) occurred. The court's finding was only that the municipality had done enough to satisfy the due diligence standard on the specific facts. Employers who skip inspections, ignore warnings, or fail to engage with safety professionals will not benefit from this decision.
Can a Municipality Be Found Liable Under the OHSA for a Hidden Hazard?
Yes — but only if it failed to take all reasonable steps to discover and address that hazard. Ontario’s Occupational Health and Safety Act imposes strict liability on employers and constructors, meaning the Crown does not need to prove intent. However, a defendant can avoid conviction by proving due diligence: that it exercised all reasonable care given the specific circumstances of the worksite.
In Ontario (Ministry of Labour, Immigration, Training and Skills Development) v. Greater Sudbury (City), 2026 ONSC 3671 (CanLII), the Ontario Superior Court of Justice overturned convictions against a municipality and entered acquittals, finding that the trial judge made errors unsupported by the evidence when concluding that additional precautions were available and ought to have been taken.
What Is the Due Diligence Defence Under the OHSA?
Due diligence means the employer took every reasonable precaution in the circumstances to prevent the violation from occurring. This is a well-established defence in Ontario regulatory law, confirmed in cases like Sault Ste. Marie and applied consistently in OHSA prosecutions.
The standard is objective but contextual. Courts look at what a reasonable employer in the same situation — with the same information, resources, and site constraints — would have done. An employer is not required to be perfect or to anticipate hazards that are genuinely unforeseeable. The question is always: given what was known and knowable, was enough done?
What Happened at the Worksite in This Case?
A worker was injured at a construction site where the municipality was the owner. The hazard involved a latent underground vault — a hidden structure that did not appear in records and was not visible during a site walkthrough. The municipality had conducted a records search and a limited on-site inspection before work began. It was the constructor, not the municipality, who had day-to-day control of the site and the relevant expertise.
At trial, the municipality was convicted. The trial judge found that other steps could have been taken. On appeal, the Superior Court found that this conclusion had no evidentiary foundation — the trial judge identified no specific alternative measures that were actually available, feasible, and within the municipality’s control given the site’s constraints.
What Standard of Review Did the Court Apply?
The court applied different standards depending on the type of question being reviewed. Pure questions of law — such as what the OHSA requires — are reviewed on a correctness standard, meaning the appeal court decides for itself whether the law was applied correctly. Questions of mixed fact and law — such as whether the specific steps taken were sufficient — are reviewed on the more deferential “palpable and overriding error” standard.
A palpable and overriding error is one that is obvious and affects the outcome of the case. The court found that the trial judge’s conclusion about available alternatives was speculative and not grounded in evidence, which met that threshold. This is consistent with the approach in Waxman and other Ontario appellate decisions on factual error.
Does the Constructor’s Role Affect the Municipality’s Liability?
Yes, and this was a significant factor in the court’s analysis. The constructor — the party with actual control over the day-to-day operations of the site — has primary responsibility for worksite safety under the OHSA. Where a constructor has the relevant expertise and control, an owner’s obligations are more limited, though not eliminated.
The court recognized that the municipality had appropriately engaged with the constructor and was entitled to rely on that party’s expertise for matters within the constructor’s domain. This does not mean owners can simply hand off all responsibility, but it does mean that the scope of an owner’s due diligence obligations is shaped by who actually controls the site.
What Does “Palpable and Overriding Error” Mean in Practice?
A palpable and overriding error is not just any disagreement with the trial judge’s findings. It is an error that is plainly visible in the record and that changes the result. In this case, the appeal court found that the trial judge speculated about alternatives — steps the municipality could have taken — without any evidence that those steps were realistic, available, or within the municipality’s power given the actual conditions at the site.
This matters because in regulatory prosecutions, the burden is on the defendant to prove due diligence. But the Crown and the court cannot fill gaps in the evidence with speculation. If a trial judge identifies a failure to take a particular precaution, there must be some evidentiary basis for concluding that precaution was actually possible.
Practical Takeaways for Employers and Municipalities Facing OHSA Charges
- Document everything before work begins. Records searches, site inspections, and communications with constructors should be recorded in writing. If a hazard was not discoverable, you need to be able to show why.
- Understand the constructor’s role. If a constructor has control over the site, make sure that relationship is clearly defined. Your due diligence obligations as an owner are shaped by what the constructor is responsible for.
- Do not assume that a conviction at trial is the end of the road. Appellate courts will overturn findings that are not supported by evidence, even in regulatory cases.
- Watch for speculative reasoning in trial decisions. If a trial judge identifies steps you “could have taken” without pointing to evidence that those steps were feasible, that may be a ground of appeal.
- Consult legal counsel early. The due diligence defence is fact-specific and requires careful preparation. Waiting until after charges are laid to gather evidence makes the defence much harder to establish.
If you are dealing with a workplace regulatory matter or need advice on a related immigration or work authorization issue, our Ontario immigration lawyers can help connect you with the right resources. For matters involving judicial review of government decisions, visit our judicial review practice page for more information.
UL Lawyers offers a free initial consultation from our Burlington office and serves clients across Ontario. If you have questions about regulatory liability, workplace law, or any related matter, reach out to our team to discuss your situation.
This article is automated commentary on a public court decision and is for general information only — not legal advice. Decisions rely on facts unique to each case. If you are affected by a similar issue, contact a lawyer for advice specific to your situation.
FAQ
Frequently asked questions
Due diligence means the employer took all reasonable precautions in the circumstances to prevent a workplace safety violation. If an employer can prove this on a balance of probabilities, they can avoid conviction even though the prohibited act occurred.
Not if the hazard was genuinely latent and undiscoverable through reasonable efforts. Ontario courts assess what the employer knew or reasonably ought to have known, and cannot convict based on speculation about steps that had no evidentiary support.
It is an obvious error in the trial judge's findings of fact that directly affects the outcome of the case. Appeal courts in Ontario will intervene when a trial judge's conclusions are not grounded in the evidence presented at trial.