Canadian OHS statutes are written as general duties — take every precaution reasonable in the circumstances — rather than as exhaustive lists of what to do. Due diligence is the other half of that design: because the duty is open-ended, the question after an incident is not “did you break rule 47” but “what had you done, before it happened, that a reasonable employer would have done”.
What it means in practice
- It is proved by records, not by intent. The hazard assessment, the training sign-offs, the inspection reports, the dated corrective actions, the minutes of the joint committee. Precautions that were taken and not written down are precautions you cannot show.
- It has to be current. A hazard assessment from four years ago for a process that changed twice since is evidence against you, not for you.
- It follows the delegation. Assigning safety to a supervisor does not move the duty; it adds one. What the employer has to show is that the supervisor was competent, instructed, resourced and supervised.
- Directors and officers are named personally in several provincial acts, so this is not only a corporate exposure.
What it is not
It is not a duty you can point at in the statute. Due diligence is a defence recognised in law, and it only ever surfaces once something has gone wrong. That is precisely why it cannot be assembled afterwards.
It is not “we followed the regulation”. Compliance with a specific standard is evidence of care, not a ceiling on it: where a foreseeable hazard is not covered by any regulation, the general duty still applies.
And it is not one standard across Canada. The federal Code applies to about six per cent of the workforce; the rest sit under provincial acts whose wording, committee thresholds and prosecution practice genuinely differ. What satisfies a Crown in Ontario is not automatically what a CNESST inspector expects in Quebec.