CALGARY -- The Government of Alberta’s provincial court of appeal challenge against the federal carbon tax entered its third and final day Wednesday. 

Lawyers for the province have been arguing in an Edmonton courtroom this week the Trudeau government’s move to impose a national tax on carbon is unconstitutional. 

Alberta said provinces have jurisdiction over the development of natural resources and electricity generation and this tax is stepping on those powers. 

On Tuesday, Ottawa fought back, claiming the climate crisis is both a national and global issue that can’t be fought separately by provinces. 

"The context of this case is the greatest existential threat of our time," said federal lawyer Sharlene Telles-Langdon in her opening arguments supporting Ottawa’s carbon tax. 

"There has been a constitutionally important transformation — we’re now in a situation where the dimensions of the problem are international and global."

Ottawa argued it has authority to impose the tax under the Constitution’s peace, order and good government clause. The claim is that this section of the Constitution allows the feds to intercede in issues of national concern. 

Langdon-Telles went on to say the carbon tax is part of Canada’s right to sign international treaties and lives up to accords including the Paris Agreement. 

Canada’s lawyers added a national minimum standard on greenhouse gas emissions must be set and is something only Parliament can address.  

Meantime, Alberta’s lawyer Peter Gall strongly disagreed and said the law can’t be justified under the national concern doctrine. 

"It really does involve a radical extension of the national concern doctrine in a way that is very invasive of provincial powers," Gall said. "In any situation where the feds believe there is pressing national concern, they can just take it over if they believe they have the best approaching approach for the dealing with the situation."

Ottawa began imposing its carbon tax this year on provinces that did not have their own systems in place. 

Alberta’s newly elected UCP government ditched the consumer carbon tax brought in by the previous NDP government and instead introduced a $30 per tonne carbon tax on industrial emitters. 

That move was approved by the federal government but Alberta will still fall under a federal carbon tax on Jan. 1. The continuing court challenge won’t change that. 

In a statement issued Monday, Alberta Justice Minister Doug Schweitzer said a federal carbon tax "is not based on the idea that Ottawa knows best."

"Each province is unique, that is why our federation is structured to give provinces the right to make our own laws and regulations over businesses when it comes to issues like reducing greenhouse gas emissions."

Legal counsel from both the federal and provincial sides have each been granted three hours to make arguments in court. A total of 13 interveners are present to make arguments on both sides of the case. 

In a rare move, the proceedings have also been livestreamed.

The court of appeal panel, comprised of five judges, is expected to deliver its decision in the coming months. Either party may appeal the decision to the Supreme Court of Canada. 

Both Ontario and Saskatchewan previously launched their own provincial appeals of the federal carbon tax. Both provinces lost but each will take their arguments to the Supreme Court of Canada in 2020. 

With files from The Canadian Press