The Court of Appeal of Alberta Tuesday ruled that Canada’s environmental Impact Assessment Act is unconstitutional. The act required some entities pursuing projects which may cause environmental harm, or harm to indigenous communities, to seek an impact assessment from Canada’s Impact Assessment agency in advance.

The court reviewed the act at the request of Alberta’s provincial government. In a 4-1 decision the justices ruled that the act exceeded the scope of the Canadian Parliament’s powers and contravened the basic principles of Canadian federalism. Specifically, the court objected to the act’s regulation of intra-provincial activities, which are normally regulated by Canadian provinces instead of the federal government.

In its decision, the court called the act an example “legislative creep,” the illegitimate extension of Parliament’s powers over the provinces. The court asserted that:

Climate change constitutes an existential threat to Canada. But climate change is not the
only existential threat facing this country. The IAA involves another existential threat – one also pressing and consequential – and that is the clear and present danger this legislative scheme presents to the division of powers guaranteed by our Constitution and thus, to Canada itself.

Almost immediately after the court released its decision, Prime Minister Justin Trudeau announced that he will appeal while Alberta Premier Jason Kenney celebrated the ruling on twitter.