The U.S. Supreme Court is hearing oral arguments today about a narrow procedural issue that could determine whether Michigan or federal courts ultimately decide the fate of a 73-year-old oil pipeline that many tribal nations say threatens their waters, treaty rights, and ways of life.

The case, Enbridge v. Nessel, centers on Line 5, a 645-mile oil pipeline that starts in Superior, Wisconsin, snakes through Michigan, and concludes in Ontario, Canada. More than half a million barrels of oil and natural gas flow through it daily. The pipeline has leaked more than 30 times inland, spilling over a million gallons of oil collectively. All 12 federally recognized tribes in Michigan have called for it to be shut down. 

The Straits of Mackinac, where the pipeline crosses between Lake Michigan and Lake Huron, are ecologically sensitive and sacred to the Ashininaabe peoples as the waters are the center of their creation story. Five tribal nations also hold treaty rights to fish and hunt in these waters, rights that predate Michigan’s statehood and are protected by federal law. 

But tribes are not parties in this particular case, which started in 2019, when Michigan Attorney General Dana Nessel sued to shut down the pipeline.

“What’s at stake on Tuesday is the authority for the state of Michigan to manage state resources and public trust matters like the lakebed,” said David Gover, Pawnee and Choctaw managing attorney at the Native American Rights Fund, which along with Earthjustice represents the Bay Mills Indian Community in its advocacy against Line 5. “It’s state sovereignty and what is the state’s ability to manage and protect their resources.”

The specific question before the court is narrow but consequential: Was a lower court right to allow Enbridge to move the case from Michigan state court to federal court more than two years after the typical 30-day deadline for such a request had passed? A year after Nessel sued, the state formally revoked the pipeline’s approval to operate, citing fishing and hunting rights and the 1836 Treaty of Washington, and warning that an oil spill in the Straits “would have severe, adverse impacts for tribal communities.” 

Michigan Governor Gretchen Whitmer sued Enbridge to enforce the revocation, but chose to drop her suit in 2021 to support the attorney general’s case in state court. A federal court then allowed Enbridge to move the state case to federal court, citing “exceptional circumstances.” Now, the Supreme Court must decide whether that was appropriate.

“Indian law cases often turn on gateway doctrines like standing, jurisdiction, and removal before courts ever reach treaty interpretation,” said Wenona Singel, citizen of the Little Traverse Bay Bands of Odawa Indians, and director of the Indigenous Law & Policy Center at Michigan State University’s College of Law. “Those procedural rulings can quietly shape outcomes. … When infrastructure operates in waters protected by treaty rights, litigation delay has environmental and cultural consequences. A procedural extension can mean years before a court reaches the underlying substance of the case.”

Debbie Chizewer, managing attorney at the environmental nonprofit Earthjustice, said an estimated 40 million people rely on the Great Lakes for freshwater and could be harmed by an oil spill. The Great Lakes hold a fifth of all the surface freshwater on Earth. “This case is really about Michigan’s ability to protect the Great Lakes from an outdated Canadian oil pipeline that’s threatening to rupture,” she said. 

Enbridge argues that concerns about pollution in the Great Lakes are overblown, noting that Line 5 continues to pass safety inspections and federal regulators have not identified any safety issues with its continued operation. The company also emphasizes that shutting down the pipeline would affect energy and foreign affairs: Line 5 supplies half the oil that Ontario and Quebec rely on, and the Canadian government opposes its closure. “The Supreme Court’s review will provide needed clarity,” an Enbridge spokesperson said.

Tuesday’s arguments are only one part of a sprawling legal and regulatory battle over Line 5. Enbridge has a separate federal lawsuit against Michigan Governor Whitmer arguing that the governor doesn’t have the right to shut down the pipeline. In March, the Michigan State Supreme Court will consider a lawsuit from several tribes and environmental groups who want to overturn a state permit to allow Enbridge to build a new tunnel under the Straits of Mackinac. Federal and state agencies are currently mulling over additionalpermits for the same rerouting project. 

And last week, the Bad River Band of Lake Superior Chippewa asked a Wisconsin state court to review yet another permit allowing Enbridge to reroute Line 5 through their watershed. 

“The Band River watershed is not an oil pipeline corridor that exists to serve Enbridge’s profits,” said Bad River Band Chairwoman Elizabeth Arbuckle. “It is our homeland. We must protect it.”  

Wenona Singel, from Michigan State University, said while the case before the U.S. Supreme Court won’t redefine treaty rights, it still matters to Indian Country. 

“It may influence how easily powerful defendants can change courts in litigation,” she said, “and how long communities must wait for judicial resolution.” 

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