The Supreme Court of Canada has ruled the federal carbon pricing law is constitutional.
The ruling found six judges entirely in favour, one partial dissent and two entirely in disagreement with the majority.
Chief Justice Richard Wagner wrote for the majority of the judges, which found the Act to be constitutional. They noted that global warming causes harm beyond provincial boundaries and that it is a matter of national concern under the "peace, order and good government" clause of the Constitution.
Canada implemented the Greenhouse Gas Pollution Pricing Act in 2019 setting a minimum price on carbon emissions in provinces which don't have an equivalent provincial price.
The Provinces of Saskatchewan, Ontario and Alberta challenged that law taking it all the way to the Supreme Court.
The Supreme Court of Canada Ruling can be found
here.