The Supreme Court of Canada ruled March 25 the federal Greenhouse Gas Pollution Act of 2018 was constitutional with six justices in the majority and three in dissent to settle a three-year jurisdictional dispute between Ottawa and the provinces over the carbon tax.There were a number of routes the majority could have taken to find this enabling legislation behind federal carbon pricing constitutional.But the majority opinion written by Chief Justice Wagner hung the decision on the Peace, Order and Good Government (POGG) clause of Section 91 of the Constitution Act, 1867.Welcome to the POGG years in federal-provincial relations.Justice Wagner wrote that climate change “is a threat of the highest order to the country and indeed to the world.” He added that “the undisputed existence of a threat to the future of humanity cannot be ignored.” The majority concluded that these matters raised the subject matter of the act to one of “national concern” within POGG.The majority added that any one province refusing to act could wreak havoc on the remaining provinces.The phrase “national concern' came from the decision in the1946 Canada Temperance Federation case. The late Peter Hogg, Canada's foremost constitutional scholar in recent times, in his book “Constitutional Law of Canada” described this concept as “the idea that some matters of legislation, in their origin local and provincial, could acquire 'national dimensions or (as it is usually now expressed) 'national concern' and thereby come within the federal Parliament's POGG power is at the core of the national concern branch of POGG.”It was Hogg's view that if the legislation by its inherent nature is of concern to the Dominion as a whole then it meets the national concern test.He also noted that there may be cases when the failure of one province to act would injure the residents of the other (cooperating) provinces. And in the matter of climate change the majority in the carbon tax case found that uniformity of law throughout the country was essential.The dissenting opinions of Justices Rowe and Brown found that the majority opinion “rewrites the role of the Constitution” and this law “is a model of federalism that rejects our Constitution and rewrites the rules of the federation.”Justice Brown wrote that “within their areas of legislative authority, provinces are not only sovereign, but exclusively so.”The concern of the minority is that the majority decision, taken to its logical conclusion could mean under the guise of legislating on climate change, the federal government could encroach or entrench on provincial matters such as education and health care.Justice Brown in dissent stated that this decision could open “the door to federal intrusion by way of national standards-into all areas of provincial jurisdiction including intra-provincial trade and commerce, health and management of natural resources. It is bound to raise serious tensions in the federation.”His concerns about provincial powers seem to be coming true before the ink is fully dry on the minority decision.We already today's federal budget will at least lay the groundwork for a national daycare system. In addition, we can expect proposed national guidelines on long-term care of the elderly.These concerns were rejected by the majority of the Court as Justice Wagner stated that legislating on matters such as building codes, public transit and home heating are not matters of national concern.  POGG can only be used when some law has a purpose that a province can't fulfill.Jonathan Wilkinson, Minister of Environment and Climate Change, agreed, saying the decision does not “open a Pandora's box in terms of federal jurisdiction.”Still, most of the provinces are bound to differ.  Standards of long-term care and child care depend on building codes and standards of heating, after all.The decision of the Court brings certainty to the legality of a federal price on carbon with a floor determined by Ottawa.  However, it still leaves undecided how the provinces of Alberta, Saskatchewan and Ontario will implement it.At this point Premier Moe of Saskatchewan seems to have the clearest sense of how he will be dealing with this decision.  Saskatchewan will come out with its own plan similar to the one adopted by New Brunswick focusing on carbon pricing for fuel.The plan would seek exemptions for different uses of fuel such as grain drying.  There would also be an offset program for sequestering carbon.Premier Kenney of Alberta stated he was disappointed by the decision, expressing concern that the Supreme Court was eroding provincial power.  He hoped this would be a one-time exception.Kenney is consulting with other provinces to determine if there is broad based interest in a cap-and-trade system.As for Ontario it remains unclear where it will land but did point to its regime for large emitters.Conservative leader Erin O'Toole maintains that a carbon tax is not the way to tackle climate change and the party is in the process of creating its own climate plan.  This plan is to focus on large industrial emitters and partnerships with provinces while reducing emissions.This decision of the Supreme Court brings to an end the debate over the legality of the federal carbon tax.  What is left for provinces is implementation of the decision under the watchful eye of the federal government.As far as judicial activism is concerned it is certainly arguable that the Court's adoption of the “national concern” doctrine is legitimate in this case.The question is whether, as suggested by the minority opinion, this doctrine may be expanded to apply to all matters energy- or environment-related, claiming any such federal legislation is climate change related and therefore a legitimate matter falling within federal jurisdiction.Federal-provincial relations are bound to be interesting in the POGG years ahead.Bruce Carson was an adviser to Prime Ministers Brian Mulroney and Stephen Harper.