Due diligence: the legal standard

Three months after the spiral conveyor injury, Harrowgate Foods Ltd. received a letter from the Department of Labour, Skills and Immigration: the company was being charged under the Occupational Health and Safety Act with failing to ensure that machinery was locked out before cleaning. Rachel called a meeting with Elena, Marcus and the company's lawyer, Aisha Grant. The first question Rachel asked was whether the company could defend the charge. Aisha's answer introduced the most important legal idea in Canadian safety law. 'The Crown will probably be able to prove the lockout wasn't done,' she said. 'The question is whether we can prove we took every reasonable precaution to prevent it. That's due diligence, and the burden is on us.'

This lesson explains what due diligence means in law, where it comes from, and the three practical duties that make it up. Lesson 7 covers how the Department enforces the law, and lesson 8 shows how an employer and a supervisor build the evidence of due diligence before anything goes wrong.

Strict liability offences

Most offences under provincial safety laws are what courts call strict liability offences. The idea comes from the Supreme Court of Canada's 1978 decision in R. v. Sault Ste. Marie, a case about pollution, which divided regulatory offences into three types. Offences requiring proof of intent, called mens rea offences, are mostly found in the Criminal Code. Absolute liability offences allow no defence at all once the act is proven. Strict liability offences sit in the middle: the prosecution must prove beyond a reasonable doubt that the prohibited act happened, but the accused can then avoid conviction by proving, on a balance of probabilities, that it took all reasonable care to prevent it, or that it reasonably believed in a mistaken set of facts which, if true, would have made the act innocent.

The court reasoned that regulatory laws protect the public, so the prosecution should not have to prove what was in a company's mind, but that it would be unfair to convict someone who had done everything reasonable. The burden of proving reasonable care therefore falls on the accused, because the accused knows what it did to prevent the harm. Canadian courts have applied this framework to occupational health and safety offences ever since, and the defence of reasonable care is what safety professionals call due diligence.

In practice, that means a safety prosecution usually turns on two questions. First, did the prohibited thing happen: was the machine not locked out, was the guard missing, was the worker untrained? That is often easy to prove after an injury. Second, can the employer prove that it took every reasonable precaution in the circumstances to prevent it? That second question is where most cases are won or lost.

What 'reasonable care' means

Due diligence does not require perfection. Courts have said repeatedly that employers are not insurers of worker safety, and that the standard is reasonable care, not every conceivable precaution. But the standard rises with the danger. Where the potential harm is death or serious injury, the care expected is high, and courts expect employers to anticipate foreseeable human error, including workers taking shortcuts under pressure. A defence that says 'our procedure prohibited it and the worker broke the rule' rarely succeeds unless the employer can show it did everything reasonable to make the rule work and to enforce it.

Courts weigh several factors in deciding whether care was reasonable. How serious and how likely was the harm? What did the industry know about the hazard, and what were others doing? What alternatives were available, and at what cost? How much control did the accused have over the situation? What knowledge and skill did the accused and its supervisors have? Was the event foreseeable? These questions are asked about the situation as it was before the incident, not with hindsight, but the incident itself often reveals what was foreseeable.

The three duties of due diligence

Lawyers and safety professionals often break due diligence into three duties. The framing is a teaching tool rather than a legal test written in any statute, but it maps well onto what courts look for, and it gives supervisors a practical way to check their own work.

The duty of foresight. The employer must look ahead and identify the hazards workers face, including foreseeable misuse and shortcuts. This is the hazard assessment duty from lesson 3. A court will ask whether the hazard that caused the incident was identified, whether the assessment reflected how the work was really done, and whether it was updated when things changed. For the spiral conveyor, the hazard had been identified, but the assessment did not reflect the shortened cleaning window or the far disconnect. That is a weakness.

The duty of efficiency. The employer must put effective controls in place to deal with the hazards it has identified: engineering controls, safe equipment, written procedures, training and protective equipment, following the hierarchy of controls. Effective means the controls actually work in practice, not only on paper. For the spiral, the lockout procedure existed and the training had been delivered, but the training was generic and the disconnect placement made the procedure hard to follow within the schedule. Another weakness.

The duty of authority. The employer must supervise the work, enforce its rules, correct unsafe behaviour and conditions when they are found, and discipline repeated or deliberate breaches fairly. This is where the spiral defence was weakest. The previous night supervisor knew lockout was being skipped and did nothing. Workers said it happened most nights. A rule that is broken routinely with a supervisor's knowledge is evidence that the employer did not exercise its authority.

Aisha summarized the position for the leadership team. The company had a procedure, locks and training, which would help. But the evidence of tolerated non-compliance, the generic training, the old hazard assessment and the time pressure from the schedule would all be used by the Crown to show that the company had not taken every reasonable precaution. The prospects of a full due diligence defence were poor.

Due diligence after the event

Due diligence is judged on what was done before the incident. What a company does afterwards cannot create a defence that did not exist. But post-incident actions still matter. They show whether the company takes the problem seriously, they can reduce the risk of a repeat, and they are relevant at sentencing if there is a conviction. Courts often take into account an employer's prompt and thorough response, its cooperation with the investigation and its willingness to accept responsibility when deciding the size of a fine.

Harrowgate Foods Ltd.'s response after the injury was strong: the floor-level disconnect and interlocked gate, the extended sanitation window, the rewritten procedure, machine-specific training and a supervisor verification step. Aisha advised that these would not defend the charge, but would weigh heavily in any sentencing and, more importantly, would protect the next worker.

Measuring readiness

After the meeting with Aisha, Elena built a simple scorecard to test due diligence in each high-risk task, scoring each of the three duties from 0 to 3 and asking for evidence for every point awarded.

# Evidence check for high-risk tasks at the main plant (0 = none, 3 = strong and documented).
tasks = {
    #                foresight efficiency authority
    "spiral clean":     (1, 1, 0),
    "mixer tank clean": (2, 2, 2),
    "slicer change":    (2, 3, 1),
    "oven maintenance": (3, 2, 2),
    "forklift loading": (2, 2, 1),
}
names = ("foresight", "efficiency", "authority")
for task, s in tasks.items():
    weakest = names[s.index(min(s))]
    print(f"{task:<17} {'/'.join(map(str, s))}  total {sum(s)}/9  weakest: {weakest}")
avg = [sum(s[i] for s in tasks.values()) / len(tasks) for i in range(3)]
print("average by duty:", dict(zip(names, [round(a, 1) for a in avg])))

spiral clean      1/1/0  total 2/9  weakest: authority
mixer tank clean  2/2/2  total 6/9  weakest: foresight
slicer change     2/3/1  total 6/9  weakest: authority
oven maintenance  3/2/2  total 7/9  weakest: efficiency
forklift loading  2/2/1  total 5/9  weakest: authority
average by duty: {'foresight': 2.0, 'efficiency': 2.0, 'authority': 1.2}

The scorecard showed the same pattern across most tasks: authority, meaning supervision and enforcement, was weakest. That told Elena where to focus supervisors' time, and it set up the work in lesson 8 on building and recording due diligence.

Due diligence for supervisors personally

Due diligence is not only a defence for employers. Supervisors and workers charged personally can raise it too, and the same three questions apply on a smaller scale. Did the supervisor know the hazards of the work they directed? Did they make sure the workers were trained and had the right equipment and procedures? Did they check, correct and enforce? A supervisor who can answer yes to each, with records to show it, is in a strong position even if a worker on their crew is hurt. A supervisor who knew about a serious breach and did nothing is in a very weak one.

This is why Elena told Dev that his supervisor log was the single most important document he would keep. When he verified lockout on the spiral, he wrote the time and his initials. When he corrected a worker who started cleaning before verification, he noted it and the follow-up. When he found a hazard, he recorded what he did and whom he told. None of this took more than a few minutes a shift. Over months, it built exactly the evidence a court would look for to judge whether he had exercised his authority.

Mistake of fact

Sault Ste. Marie also allows a second branch of the defence: that the accused reasonably believed in a mistaken set of facts which, if true, would have made the act innocent. In safety cases this branch is narrower and less often used. An example would be a supervisor who checked that a machine had been locked out, saw a lock and tag on the disconnect and reasonably believed the machine was isolated, when in fact a contractor had wired a second, undocumented power feed. The belief must be honest and reasonable, and the accused must have taken reasonable steps to check. Wishful thinking or failing to look is not a reasonable mistake.

How the courts see due diligence today

Decades of decisions have settled into a fairly consistent picture. Courts reward employers that identify hazards realistically, choose strong controls, train for the actual job, supervise actively, enforce consistently and keep records of all of it. They are sceptical of programs that look impressive on paper but are not followed on the floor, and of defences that blame the injured worker for a shortcut that supervisors had tolerated. The most persuasive evidence is usually ordinary and routine: inspection records, completed checklists, coaching notes, discipline for repeated breaches and responses to committee recommendations, created long before anyone imagined a prosecution.