Attorney General of Ontario v. Attorney General of Canada

(Ontario) (Civil) (As of Right)


Constitutional law - Division of powers - Environmental law - Climate change - Power to tax and to regulate - Whether the Greenhouse Gas Pollution Pricing Act, S.C. 2018, c. 12, s. 186, falls within the national concern branch of the Peace, Order, and Good Government power - Whether the Act imposes valid regulatory charges or valid taxation - Constitution Act, 1867, s. 91.


Case summaries are prepared by the Office of the Registrar of the Supreme Court of Canada (Law Branch). Please note that summaries are not provided to the Judges of the Court. They are placed on the Court file and website for information purposes only.

By Order in Council 1014/2018, the Lieutenant Governor in Council referred the following question to the Court of Appeal for Ontario pursuant to s. 8 of the Courts of Justice Act, R.S.O. 1990, c. C.43:

Whether the Greenhouse Gas Pollution Pricing Act, Part 5 of the Budget Implementation Act, 2018, No. 1, S.C. 2018, c. 12, is unconstitutional in whole or in part.

A majority of the Court of Appeal for Ontario found the Act constitutional. In concurring reasons, Hoy A.C.J. found the Act constitutional but for reasons different from the majority. In a dissenting opinion, Huscroft J.A. would have found the Act unconstitutional.

Lower Court Rulings

June 28, 2019
Court of Appeal for Ontario

2019 ONCA 544, C65807
See file.