R v Sault Ste-Marie (City of) [1978] 2 SCR 1299 is a Supreme Court of Canada case where the Court defines the three types of offences that exist in Canadian law and further defines the justification for "public welfare" offences.

The city built a disposal site 20 feet from a stream which, when filled by the disposal company, resulted in waste seeping into the stream.

The city was charged with discharging, or permitting to be discharged, refuse into the public waterways causing pollution pursuant to section 32(1) of the Ontario Water Resources Act.

The Court of Appeal for Ontario held that the charge required proof of mens rea, which on the facts would acquit the defendant.

In the judgement written by Justice Dickson, the Court recognized three categories of offences: To distinguish between these types the Court examines: The Court then noted that the dumping offences were of a public welfare nature and were from a provincial statute, thus, were Strict Liability offences and do not require mens rea.