Workplace hazard disclosure and the limits of owner liability under the Occupational Health and Safety Act
A recent Ontario Superior Court of Justice appellate decision has important implications for both owners/employers and constructors when it comes to workplace hazard disclosure. In Ontario (Ministry of Labour, Immigration, Training and Skills Development) v. Greater Sudbury (City), 2026 ONSC 3671, the Court overturned a trial judge’s decision that had convicted the City of Sudbury (the City) of two offences under the Occupational Health and Safety Act (the OHSA) for failing to ensure worker safety and notify the constructor of hazards at a worksite.
The Court found that the trial judge had erred in rejecting the City’s due diligence defence, noting that the City had indeed taken reasonable steps to investigate and communicate potential safety hazards to the constructor. The Court also found that the trial judge’s suggestion that “other steps” were available to the owner was speculation and unsupported by the evidentiary record.
This decision reinforces that even if an owner/employer fails to notify a constructor of a workplace hazard that results in injury, the owner/employer may avoid liability by establishing a due diligence defence. However, the defence will be available only if the hazard was unforeseeable and the owner/employer can demonstrate that reasonable steps were taken to comply with their OHSA obligations.
Background
In 2022, the City hired an external constructor, C.K. Construction (CK), to carry out a rehabilitation project on a city-owned property. Before work began, the City searched its internal archives and municipal records relating to the worksite but found nothing. The City also conducted a site walk-through with CK to identify potential hazards it was aware of. Neither the records search nor the walk-through revealed decommissioned drinking fountain service box hidden underground. During the project, a mobile elevating work platform carrying a CK worker sank into this hidden structure, tipping the basket and seriously injuring the worker.
The trial judge convicted the City on both counts: (1) failure to provide information, instruction and supervision to protect worker health and safety; and (2) failure to acquaint a worker with a hazard in the workplace. The trial judge found the City’s efforts “perfunctory and clearly inadequate” and suggested “other steps were available, such as a more robust site inspection.” The City appealed.
The appeal decision
The Court held that the trial judge failed to properly consider what steps were actually available to the City and whether the causes of the offence were within the City’s control. The Court identified three ways an owner/employer could fulfil its due diligence requirements:
- an extensive search of municipal records involving the worksite;
- a walk-through of the site; and
- actual knowledge of the hazard.
The Court noted that the City did conduct an exhaustive records search, which (a) did not reveal any underground water line, and (b) disclosed no records or as-built drawings of the site, a risk the contractor accepted when it took on the project.
The Court also rejected the trial judge’s reasoning that the City should have walked through the “entire site” with the contractor at the kick-off meeting. A complete walkthrough was simply not possible given the site conditions, which were the very reason the City hired CK in the first place. The Court reaffirmed that when an owner/employer cannot safely undertake work on its own, it is entitled to hire an external constructor with the requisite experience and expertise to do so.
The Court concluded that the trial judge’s findings were unsupported by the evidence. Given the lack of internal records, the City’s lack of knowledge about the underground structure, and the inherent limitations imposed by the site conditions, Justice Cornell found that the City took all reasonable efforts to comply with its statutory obligations. The appeal was allowed and the City was acquitted on both counts.
Key takeaways
This case has significant implications for constructors and for owners/employers who hire them:
- With great expertise comes great responsibility
The City was held not liable in part because it lacked the skill to undertake the restoration work that would have been required for a complete site walk-through. Indeed, that was CK’s domain. The Court noted that CK bore responsibility for “ensuring that site conditions were such that a mobile elevating work platform could safely be used.”
The lesson for constructors is clear: your expertise comes with a corresponding responsibility to independently assess site conditions before work begins. You cannot simply rely on information provided by the owner/employer. If an owner unknowingly fails to disclose a hazard, you may still be held liable for any resulting injuries. Proactive risk assessment is essential.
- “Reasonable care” does not demand an unreasonable level of employer foresight
This case also provides reassurance for owners and employers: courts will not hold you to an impossible standard of foresight. The level of “reasonable care” in a due diligence defence is judged based on what was actually discoverable at the time and not against a standard of perfection or through the lens of hindsight.
However, constructors should never assume that an owner’s disclosures are exhaustive. Independent risk assessments are critical, especially on sites with conditions that may conceal hazards, such as thick vegetation, accumulated topsoil, or aging infrastructure. Do not take disclosures at face value; verify them yourself.
- Leave a paper trail
This may sound like repetitive advice from lawyers, but this case demonstrates exactly why it matters. Much of the Court’s analysis turned on the documented communications between the parties: what hazards were disclosed, what was discussed at the kick-off meeting and what limitations prevented a full site walkthrough. Both owner/employers and constructors should treat site records, meetings and site walk-throughs as opportunities to create a clear paper trail to help their defence.
The bottom line
This decision reminds us that while owners and employers must take reasonable steps to identify and disclose workplace hazards, the law does not demand perfection. If a hazard is genuinely undiscoverable despite diligent efforts, a due diligence defence may succeed. For constructors, the message is clear: you cannot rely solely on an owner’s disclosures. Your expertise carries a corresponding duty to independently assess site conditions. If a hidden hazard causes injury, you may be the one facing liability. The prudent approach is to conduct thorough, independent risk assessments at the outset of every project, document all communications regarding hazards, and ensure your team follows hazard assessment protocols diligently.
