What is the difference between a criminal offence and a prohibition for the protection of the public?

The distinction between an enactment which creates a crime in its real sense, and an enactment which creates a prohibition for the protection of the public, irrespective of the knowledge or intent of the person to whom the prohibition is directed, was reviewed by Cartwright J. (later C.J.C.) in Beaver v. The Queen, 1957 CanLII 14 (SCC), [1957] S.C.R. 531 at 539, 26 C.R. 193, 118 C.C.C. 129, when he said: “As to the first of these reasons, I can discern little similarity between a statute designed, by forbidding the sale of unsound meat, to ensure that the supply available to the public shall be wholesome, and a statute making it a serious crime to possess or deal in narcotics; the one is to ensure that a lawful and necessary trade shall be carried on in a manner not to endanger the public health, the other to forbid altogether conduct regarded as harmful in itself. As a necessary feature of his trade, the butcher holds himself out as selling meat fit for consumption; he warrants that quality; and it is part of his duty as trader to see that the merchandise is wholesome. The statute simply converts that civil personal duty into a public duty.”