Last week, at the Council of the Federation talks in Saint Andrews, New Brunswick, Ontario Premier, Doug Ford announced Ontario's intention to intervene in Saskatchewan's court reference to the Saskatchewan Court of Appeal challenging the Federal government's proposed carbon tax.

The court reference, which was submitted by the Province of Saskatchewan to the Court of Appeal in April of 2018, asks Saskatchewan's highest court to determine whether the federal government has constitutional jurisdiction to impose the carbon tax. The Province framed its question to the Court of Appeal as follows:

"Gas Pollution Pricing Act was introduced into Parliament on March 28, 2018 as Part 5 of Bill C-74. If enacted, will this Act be unconstitutional in whole or in part?"

Canada's Constitution sets out the subject matter over which the provinces and the federal government have exclusive jurisdiction to legislate. Section 91 outlines the areas of exclusive federal jurisdiction, which includes "regulation of trade and commerce" and taxation. The exclusive classes of jurisdiction of the provinces are set out in Section 92 and includes "property and civil rights in the province". "Carbon tax" is not an enumerated head of power in Canada's Constitution, and as such, Saskatchewan has asked the court to decide who has the exclusive jurisdiction to legislate such a regime.

As an intervener, Ontario will support Saskatchewan's position that only the provinces have the constitutional jurisdiction to enact legislation imposing a carbon tax. Saskatchewan's Premier, Scott Moe, has also indicated that Saskatchewan will seek the support of other provinces in the court challenge. It is yet to be determined whether any other provinces will join Ontario and Saskatchewan; however, some legal experts have opined that a jurisdictional challenge to the Federal Carbon tax is unlikely to succeed, which may deter some provinces from joining the legal challenge.

Whatever the outcome, the court's decision on Saskatchewan's court reference will be a significant legal development concerning the Federal government's ability to regulate provincial climate change efforts.

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