It's a federal regulatory requirement that the officer be satisfied that the individual can successfully economically establish. In the overwhelming majority of cases the federal visa officer agrees, as indicated by the 97% approval rates—so there's a 3% refusal rate, which includes refusals on health and security. There are exceptional cases where the two levels of government differ in their view, and ultimately the federal government will make the final decision, in consultation with the province.
On December 1st, 2011. See this statement in context.