In effect, yes, it does require provincial approval. For one, healthcare is purely the purview of the province. The federal government has no ability to force

In effect, yes, it does require provincial approval. For one, healthcare is purely the purview of the province. The federal government has no ability to force provinces to treat drug use as a healthcare issue. Secondly, enforcement of laws in BC is a mix of both provincial and federal and this gives the provincial government leeway. In BC, the RCMP is responsible for both provincial and federal enforcement. One of the earlier marijuana legalization efforts in British Columbia, which was supported by mayors and previous provincial ministers, hinged on enforcement. The plan was effectively to order law enforcement to not enforce marijuana laws. The province itself couldn't strike the law, but they could effectively not comply. Admittedly this is a grey area, which theoretically would require the courts to sort out, but in practice it shows some viability of the approach. In general, Canada's governments skews heavily towards provinces rather than federal (unlike the USA which has a very big federal government, most Canadian gov employees are provincial). Provinces have had the upper hand since Confederation and have been unwilling to give up much power. As such, I doubt how much approval the province needs from the federal for an action like this.