Skip to main content

An aboveground section of Enbridge's Line 5 at the Mackinaw City, Mich., pump station in October 2016.John Flesher/The Associated Press

The State of Michigan argues in a new court filing that a 1977 treaty between Canada and the United States has no bearing on what it considers its right to unilaterally shut down the Enbridge Line 5, a crucial petroleum supply for Ontario and Quebec that runs through the Great Lakes region.

Last fall, Michigan Governor Gretchen Whitmer revoked an easement permit first granted in 1953 that allows Line 5 to cross the Straits of Mackinac waterway, citing the risk of oil spills and calling it a “ticking time bomb.” She gave Enbridge until May 12 to comply and warned the company it would be breaking the law after that.

Line 5 pipeline: What you need to know about the Enbridge route now at the centre of a U.S.-Canada legal dispute

Calgary-based Enbridge has challenged these actions in U.S. federal court, arguing only the federal government can pass judgment on the safety of a pipeline. And the company defied Ms. Whitmer, saying it would not shut the line down unless ordered to do so by a judge. The state is seeking to have the matter sent back to state-level court. Enbridge and Michigan are now in court-ordered mediation talks.

In earlier legal filings, Canada and Enbridge have cited a 1977 treaty between Canada and the United States that was designed to ensure “uninterrupted transmission by pipeline” of petroleum passing through each side’s territory. The treaty says the only justifications for impeding the flow are natural disasters or emergencies – and these may only be temporary interruptions. The Canadian government argued in a May 11 filing that this represents a “solemn and reciprocal commitment to Canada ... not to interfere with the operations of international [oil and gas] pipelines” without specific justifications, including emergencies or natural disasters.

Canada has also publicly warned it is prepared to invoke the 1977 treaty, which calls for binding arbitration to settle disputes. In its May legal brief, Ottawa said it’s already in talks with Washington about its rights under the agreement.

But Michigan Attorney-General Dana Nessel, in a June 1 court filing, said the matter should be returned to a state-level court and that the 1977 pipeline transit treaty between Canada and the U.S. does not impinge on the state’s power to manage the Straits of Mackinac. “The state is aware of no other cases in which this treaty has been invoked as a basis for pre-empting a state’s claim of ownership and control of submerged lands underlying navigable waters,” the Attorney-General’s filing says.

The state even argues the treaty has no application to a dispute over whether a pipeline can cross a waterway in Michigan.

“The treaty is relevant – if at all – only in cases involving fossil-fuel pipelines running between Canada and the United States,” the Michigan filing says.

Line 5 is a vital conduit of petroleum for Ontario and Quebec. The Canadian Chamber of Commerce has warned of significant disruption to fuel supplies to Canada’s two most populous provinces if Line 5 ceases operation, while the federal government has said a shutdown would represent a threat to the country’s energy security. “Line 5 supplies approximately 66 per cent of Quebec’s crude oil needs and about 50 per cent of the [petroleum] used by Ontario’s refineries to make gasoline and other fuels,” Ottawa argued in its May brief.

Michigan in its filing also questioned whether Canada and the U.S. are really negotiating on Line 5 at all.

Canada’s legal brief had argued that the U.S. federal court should hold off on a ruling until Canada and the U.S. sort out negotiations on the future of Line 5.

“Neither this court nor any state court should act in a way that bypasses and undermines the treaty. This court should hold this case in abeyance pending the outcome of the treaty process,” the Canadian brief in May had argued.

But Michigan disputes the notion there are any talks taking place.

“The Government of Canada mistakenly suggests that there are ongoing negotiations between the United States and Canadian governments within the dispute resolution provisions of ... the 1977 transit treaty,” the state filing says.

“While there have apparently been communications between officials of each government, there is no evidence that negotiations under the treaty itself are in progress.”

Michigan argues that Enbridge’s pleadings have failed to justify keeping the matter in federal court. It says the federal Submerged Lands Act and court rulings have made it clear “state law governs disputes over property rights in the beds of inland navigable waters,” such as the Straits of Mackinac.

In a statement Wednesday, Enbridge said it believes it has presented ample evidence to demonstrate the matter should remain in federal U.S. court.

“Any attempt to shut down Line 5 has serious ramifications under an international treaty and raises substantial questions of federal law relating to interstate commerce and federal jurisdiction on pipeline safety issues. ... A federal court is needed to uniformly apply federal law in a way that promotes the energy interests of the U.S. and is sensitive to U.S.-Canada foreign relations concerning critical infrastructure like Line 5.”

Enbridge said court-ordered mediation with Michigan continues and it’s hopeful it will lead to a positive outcome for Michiganders and all those that rely on Line 5′s safe and reliable operation. The company has proposed building a US$500-million tunnel that would run deep under the straits so the Great Lakes would be shielded from spills.

Our Morning Update and Evening Update newsletters are written by Globe editors, giving you a concise summary of the day’s most important headlines. Sign up today.