Sault Ste. Marie and the due diligence defence

In R. v. Sault Ste. Marie, [1978] 2 S.C.R. 1299, the Supreme Court explained the distinction between offences requiring proof of fault, strict liability offences, and absolute liability offences. For strict liability, a due diligence defence can be available after the prosecution proves the prohibited act.

The case arose from a municipal waste-disposal arrangement and an allegation of water pollution under Ontario legislation. It supplied a structured approach to public-welfare offences that did not assume every offence required proof of a guilty mind or imposed liability without any available defence. The classification depends on the governing law. That context matters when considering modern regulatory charges: the decision offers a framework, while the actual statute and later applicable authorities determine how a particular allegation must be assessed.

The case does not make due diligence a defence to every regulatory charge. The wording and classification of the particular offence matter. In a qualifying Ontario provincial offence, records of inspections, training, maintenance, precautions, or a reasonable mistake of fact may be relevant to the applicable defence. Preserve what was actually done before the event. A policy written after receiving a charge does not establish the precautions taken at the time.

For a due-diligence assessment, assemble records of precautions actually taken before the incident. Training logs, inspection records, maintenance work, instructions, supervision, and responses to known problems may be relevant according to the offence. Explain how those measures addressed the risk that materialized, and identify any genuine gaps. A binder of policies is less useful if there is no evidence they were followed. Improvements made after the event may be sensible, but should be dated honestly. The defence must be evaluated against the legal test and facts rather than a general claim that the business usually tries to comply.

Sources

• R v Sault Ste Marie 1978 2 SCR 1299
• Provincial Offences Act

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General Ontario legal information, not legal advice for your matter, and reading it does not create a retainer. Sources checked 15 October 2026: check the current law, forms and dates before you act.

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This article is general information for people in Ontario, not legal advice. Rules, forms and deadlines change, and every situation is different. Check the current rule or speak to a licensed legal professional before you act.