The province of Ontario (Canada) has lodged an appeal against the federal carbon tax at the Supreme Court, claiming that the new contribution was unconstitutional. In June 2019, the Ontario Court of Appeal rejected Ontario’s claim, prompting the province to file an appeal to a higher court.
Canada's nationwide climate-change strategy includes a carbon tax, which must be either adopted by the provinces or imposed by the federal government. The tax will rise by CAD10/tCO2eq (around US$7.6/tCO2eq) each year from CAD20/tCO2eq (around US$15.3/tCO2eq) in 2019 to CAD50/tCO2eq (around US$38/tCO2eq) by 2022. Manitoba, Ontario, New Brunswick and Saskatchewan refused to comply with the federal plan, whereas Alberta repealed the carbon tax it had implemented in May 2019. Consequently, the federal "backstop" mechanism applies in these provinces since April 2019 (as of 1 January 2020 for Alberta).
Saskatchewan, Alberta and Manitoba governments have filed similar lawsuits against the carbon tax. A favorable ruling from the Supreme Court on Ontario’s case could allow them to remove the levy.