The Senate transport committee’s report recommending that the Liberal government’s bill on banning oil tanker traffic on the northern Pacific coast not proceed, calls it “unconstitutional and destructive to the fabric of Canadian federalism.”

The sharply-worded report submitted Monday evening to the full Senate by committee chair, Conservative Sen. David Tkachuk, criticizes Bill C-48 as “prejudicial to the economic and social interests of oil-producing provinces” and questions that it is based on sound science.

It stated that the bill “cannot be viewed separately from other government initiatives and legislation,” and that, taken together, “are having a ruinous effect on Canada’s resource industry and economy.”

Tkachuk’s report also asserts that while it is “atypical” for a Senate committee to recommend that a bill not proceed, “it is equally atypical for a sitting government to intentionally harm the economic potential of one region of Canada.”

The government bill would ban oil tankers carrying more than 12,500 metric tonnes of crude oil from stopping at ports or marine installations located along British Columbia’s northern coast. The Liberals had pledged ahead of the 2015 federal election to “formalize a moratorium on tanker traffic in the region.”

But last month, the Senate transport committee, made up of 12 appointed Senators, recommended that the bill not proceed based on a 6-6 vote.

The legislation has been vigorously opposed by Canada’s oil and gas sector and conservative and Western politicians who believe it will harm getting energy exports to market.

In contrast, environment and First Nations groups have urged un-elected Senators opposed to the bill to back off and follow the will of the elected government.

The full Senate will have its say Tuesday on whether to pass the committee’s recommendation.

Environment Minister Catherine McKenna said while the government is open to improving any piece of legislation, C-48 must “go through,” with the policy explicitly promised by the Liberals on the campaign trail.

“C-48 is an important piece of legislation. It’s something we campaigned on, we’re elected on,” she told iPolitics, noting that she had not yet read the report.

“It is part of the minister’s mandate — it passed through the House of Commons,” McKenna added.

The committee report also cited testimony from a Transport Canada official, who had said one of the reasons why the government views a tanker ban as important is that the northern coast’s waters are not well understood.

The report stated that a “lack of good data might justify a three or five year moratorium, pending those studies” but not sufficient as a cause for a permanent ban.

Tkachuk’s report also called the legislation “unconstitutional,” noting that the Lax Kw’alaams, a First Nations in northern B.C. have filed an injunction in B.C’s Supreme Court against it. The Nisga’a Lisims Band have also opposed the bill.

Transport Minister Marc Garneau published an op-ed on his Facebook page Tuesday calling on Senators to support his legislation. In it, he stated that criticisms that the bill is arbitrary and unjustified” couldn’t be “further from the truth.”

He cited four policy reasons for Bill C-48: that the area is of ecological significance, that federal and provincial governments ought to continue a legacy of extending special protections to the region, that the northern B.C. coast’s size and navigational hazards make clean-up more difficult, and that it is a response to calls from locals that include Indigenous communities.

Tkachuk’s report also states that Garneau didn’t offer a commitment to accept any of the amendments ideas that the committee had raised during his testimony, which included a review of the ban after 3 to 10 years.

READ MORE: Coastal First Nations demand Senate approve tanker ban as bill faces uncertain fate

A Senate source previously told iPolitics that a required review of the ban after a certain number of years could potentially be accepted by the government.

-with files from Marco Vigliotti