The British Columbia government is creating more uncertainty around Kinder Morgan Inc.'s Trans Mountain pipeline expansion project with a proposal to restrict any increase in diluted bitumen shipments until it conducts more spill response studies.

Provincial Environment Minister George Heyman says there needs to be more confidence in how well oil transporters are prepared to respond and mitigate the effects of a potential spill.

"It's clear from our perspective that there is a tremendous risk to our economy and our environment from a spill of diluted bitumen," Heyman told CBC News.

"British Columbians expect us to defend our coastline, our waterways in the interior of the province, and our economic and environment interests overall," he said.

But Alberta Premier Rachel Notley is slamming the B.C. proposal, calling it unconstitutional.

"The B.C. government has every right to consult on whatever it pleases with its citizens," she told reporters in Edmonton.

"It does not have the right to rewrite our constitution and assume powers for itself that it does not have. If it did, our confederation would be meaningless," she said.

Jason Kenney, leader of Alberta's Official Opposition United Conservative Party, said he would take B.C. to court if he were premier.

"I would be giving notice to the government of British Columbia of our intention to seek an application from the courts to suspend these illegal and unconstitutional regulations by the British Columbia government," Kenney said.

The B.C .government will also establish an independent scientific advisory panel to make recommendations to the minister on whether, and how, heavy oils can be safely transported and cleaned up if spilled.

Constitution 'a huge grey area'

David Boyd, an associate professor of environmental law with the University of British Columbia, says concerns about constitutionality are premature.

He says the constitution is silent on the environment, which creates "a huge grey area", and there is reason to believe the province could create a law that conforms to it.

"Until we see the actual draft regulation, it's almost impossible to determine whether it passes constitutional muster," he said.

"You can't file a legal action against a press release. So she can shoot her mouth … but that's about all she can do."

Jocelyn Stacey with UBC's Peter A. Allard School of Law says B.C. has the right to enact regulations around environmental management and emergency response.

"The question is what happens when those regulations purport to apply to a federal project. That's the question that Premier Notley is responding to," she said.

She says Trans Mountain is well within its rights to challenge any new regulations, but added environmental approvals are just one step and B.C. adding new approval criteria is not a departure from past practices.

"This is all part of the regulatory framework in which a major project operates."

More uncertainty for Kinder Morgan

The restriction creates more uncertainty for the already delayed Trans Mountain expansion project, which would nearly triple the capacity of the current pipeline system to 890,000 barrels a day.

In a statement from Kinder Morgan, a representative said Tuesday the company was aware of the government's announcement and will "actively participate in their engagement and feedback process."

It added that "the expansion project's approval by the government of Canada followed a rigorous and lengthy regulatory process that included a thorough examination of the pipeline and products being shipped."

It mentioned the conditions on the Kinder Morgan project related to diluted bitumen.

'A move in the right direction'

B.C. says it will also seek input from First Nations, industry, local governments and environmental groups, as well as the general public over the coming months.

Rueben George of the Sacred Trust says the BC government's proposal is a step in the right direction. The Trust is an initiative of the Tsleil-Waututh Nation with a mandate to stop Kinder Morgan’s new Trans Mountain pipeline and tanker project.

Reuben George of the Sacred Trust, a group mandated to stop the Kinder Morgan pipeline expansion, says he's heartened that the provincial government is proposing more measures to protect B.C.'s environment from spills.

"This is a move in the right direction. I hope the province will follow through and make the right choice," George said.

Sierra Club B.C. said it applauds the proposal, calling it a move to protect the safety and health of people in the province, and calling it a "wrench" in the company's plans.

"If I was an investor in Kinder Morgan, today's announcement would be a wake-up call that this pipeline is a risky venture," spokesperson Caitlyn Vernon said.

"Even if Kinder Morgan and federal government keep pushing to build the pipeline, they could build their pipeline, but with these new regulations they won't be able to turn the tap on," she said.

The public can provide input online once an intentions paper is released, sometime before the end of February.