Case In Point
Ontario Superior Court Provides Guidance on Navigating Due Diligence Under OHSA
Date: August 27, 2026
Employers navigating due diligence under the Occupational Health and Safety Act (OHSA), should take note of Ontario (Ministry of Labour, Immigration, Training and Skills Development) v. Greater Sudbury (City), on appeal from a trial conviction, where Justice R. Dan Cornell of the Ontario Superior Court of Justice (ONSC) acquitted the City of Greater Sudbury (the City) of two offences under OHSA: failing to provide information, instruction and supervision to protect health or safety (s. 25(2)(a)); and failing to acquaint a worker, or a person in authority over a worker, with any hazard in the work (s. 25(2)(d)). Because the actus reus was conceded and the offences are strict liability, the sole issue before the Court was whether the City had established the due diligence defence, having taken all reasonable care in the circumstances.
The decision is significant for employers navigating due diligence under OHSA. It affirms that due diligence is not a standard of perfection but a fact-driven inquiry measured against what was genuinely within the accused’s control. It confirms that an owner can discharge its statutory obligation by retaining a qualified contractor, that a latent hazard unknown to both owner and expert will not defeat the defence, and that a court cannot reject due diligence by speculating about “other steps” that were never established in evidence.
Background
Approximately 60 years prior to the decision, the City acquired six tall concrete silos, a local landmark known as the Flour Mill site, from a former flour mill operation. The silos were in disrepair, and the site was overgrown with vegetation and contained biohazards consisting of hypodermic needles.
The City hired C.K. Construction (C.K.) to rehabilitate the site for public use, including removing the biohazards, clearing up the vegetation, repairing a fence, and repairing loose concrete and brick on the concrete silos. C.K. used a mobile elevating platform for the work.
The incident was caused by a previously unknown underground utility vault, covered by a soil-covered concrete slab. There was no visible sign of the slab’s existence.
After certain work on the silos was completed, the ground foreman issued an “all clear,” and the platform began descending from approximately 90 feet with a C.K. employee inside. During this descent, the platform’s left front wheel broke through the concrete slab and sank into the unknown vault; the basket tipped and fell to the ground, seriously injuring the C.K. employee inside.
The Ministry of Labour laid two charges against the City under ss. 25(2)(a) and (d) of OHSA, which require employers to:
(a) provide information, instruction and supervision to a worker to protect the health or safety of the worker;
…
(d) acquaint a worker or a person in authority over a worker with any hazard in the work and in the handling, storage, use, disposal and transport of any article, device, equipment or a biological, chemical or physical agent;
Trial Court Convicts City Finding it Did Not Establish Due Diligence
The parties proceeded on an Agreed Statement of Facts, which included that the cause of the incident was inadequate ground support for the platform’s tire load: the left front wheel sat directly on a soil-covered concrete slab spanning the walls of an old underground utility vault that could not support the platform’s tire load. The slab collapsed, the platform’s wheel fell into the vault, and the platform tipped.
Finding that the City failed to provide information to protect C.K.’s workers and failed to acquaint them with the workplace hazards, the trial judge held that the City had not established due diligence because “other steps were available,” such as “a more robust site inspection.” She emphasized that “the entire site was not walked with C.K. at the kick-off meeting.”
The City was convicted on count one (s. 25(2)(a)). The count two conviction (s. 25(2)(d)) was stayed pursuant to the rule against multiple convictions in R. v. Kienapple.
Appeal Court Acquits City Finding it Did Establish Due Diligence
On appeal to the ONSC, the due diligence determination, a question of mixed fact and law, was reviewable for palpable and overriding error. Questions of law were reviewable for correctness.
Justice Cornell reviewed the governing authorities. In R. v. Sault Ste. Marie, the Supreme Court held that an accused may avoid liability for a strict liability offence by proving it took all reasonable care, based on what a reasonable person would have done in the circumstances. In R. v. Gonder, the court described reasonable care as a variable standard tied to each case’s special circumstances, governed by factors including the gravity of potential harm, the alternatives available to the accused, the likelihood of harm, the degree of knowledge or skill expected, and the extent to which underlying causes of the offence are beyond the accused’s control. In R. v. Greater Sudbury (City), the Supreme Court confirmed that due diligence is not a standard of perfection and that “what could have been done” is limited to steps or measures within the actor’s control. The Court held that the trial judge failed to weigh the Gonder factors of available alternatives and causes beyond the accused’s control.
Justice Cornell then examined what the City could have done to meet the reasonable due diligence requirements:
- Records: An extensive search of municipal records disclosed no records or drawings of the underground structure.
- Site examination: The kick-off examination was limited by vegetation, accumulated topsoil, and biohazards.
- Actual Knowledge: It was uncontested that the City had no knowledge of the underground structure that caused the collapse.
- A more comprehensive walk through: Even a full walk-throughwould not have revealed the structure; its surface was “unremarkable” and buried under topsoil. C.K. was also unaware of the structure, having driven a skid steer over the area.
The Court emphasized that, “The law is clear that an owner/employer can hire an entity with the experience and expertise to undertake work that cannot be safely performed by an owner/employer.” C.K. was such a contractor and it was hired to remove the vegetation and biohazards that prevented a full walk of the site.
The Court also held that the trial judge’s conclusion that “other steps were available” was unsupported by the evidence: no other steps were in evidence at trial, and the alternatives raised on appeal (using Lidar or excavation) were not possible until the vegetation and biohazards were removed. The Court concluded that the City made all reasonable efforts to provide information and a safe work site, complying with its statutory obligations. The hazard (the underground structure) “was a latent defect of which both the City and C.K. had no knowledge whatsoever.”
The Court found that the trial judge’s conclusions were not supported by the evidence and amounted to palpable and overriding error, allowed the appeal and acquitted the City on both counts.
Key Takeaways
- Due diligence is not a standard of perfection; it is assessed against each case’s specific circumstances, asking what a reasonable person would have done given what was within the actor’s control (Sault Ste. Marie; Gonder; Greater Sudbury).
- Courts applying the Gonder factors will often weigh the alternatives available to the accused and the extent to which the event’s underlying causes were beyond their control.
- An owner/employer may discharge its due diligence obligations by retaining a qualified, experienced contractor for work the owner cannot safely perform itself.
- A genuinely latent hazard that is unknown to both owner and expert contractor, and not discoverable through reasonable inspection, will not defeat a due diligence defence.
- A finding that “other steps were available” must rest on evidence, not speculation about untaken and unworkable measures.
- When retaining experts for potentially unsafe sites, employers should consult available records, disclose known or potential hazards, and review the site with those it hired to the extent it is safe to do so.
If you require further information or would like advice on other workplace safety issues, please contact your Hicks Morley lawyer.
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