The U.S. Supreme Court on Wednesday handed Michigan’s Democratic Attorney General Dana Nessel a victory, offering a unanimous decision that laid to rest a yearslong debate over whether her case to shut down Enbridge’s Line 5 pipeline should be heard in state or federal court. 

In an 14-page opinion penned by Justice Sonia Sotomayor, the court held that Enbridge had missed its 30-day window to have the case removed to federal court, with the Canadian energy company making its request 887 days after receiving Nessel’s initial complaint. 

The company’s Line 5 pipeline has been a long-running concern for tribal nations and environmentalists in the region, with Nessel calling it a “ticking time bomb” for the Great Lakes.

Running from northwestern Wisconsin into Sarnia, Ontario, the 645-mile long pipeline passes through Michigan’s Upper Peninsula, with a four-mile segment of dual pipelines running through the Straits of Mackinac, where Lake Huron and Lake Michigan meet. The pipeline carries up to 23 million gallons of crude oil and natural gas liquids through the straits each day.

“Today’s decision honors the truth that the Straits of Mackinac are not a bargaining chip and reaffirms what Tribal Nations have always known – we have the right and the responsibility to protect the Great Lakes,” Bay Mills Indian Community President Whitney Gravelle said in a statement. “The Supreme Court saw through Enbridge’s delay tactics and upheld the rule of law. This is a victory for our waters, our treaty rights, and the next seven generations who depend on the Great Lakes for life itself.”

In an emailed statement, Enbridge spokesperson Ryan Duffy noted that Nessel’s case has been stayed, awaiting the results of an appeal in another court case, which Enbridge filed against Michigan Gov. Gretchen Whitmer and the director of the Michigan Department of Natural Resources after they revoked the company’s easement to operate Line 5 in the Straits of Mackinac.

The United States District Court for the Western District of Michigan in December ruled that the move was unenforceable, with the Pipeline Safety Act of 1992 preempting states from placing safety regulations on interstate pipelines. Whitmer has appealed the decision.

“Setting aside the procedural decision, the fact remains that the safety of Line 5 is regulated exclusively by the Pipeline and Hazardous Materials Safety Administration,” Duffy said, noting that the agency has not identified any safety issues that would warrant its shutdown.

The Trump administration on Wednesday issued a presidential permit for Enbridge’s Line 5 pipeline crossing at the St. Clair River, renewing federal authorization for the decades-old infrastructure as part of a broader push to bolster cross-border oil transport.

The permit replaces a 1991 authorization for the Michigan crossing near Marysville in St. Clair County and allows the Canadian company to continue operating and maintaining the existing pipeline facilities at the international boundary. It applies only to the St. Clair River border crossing and does not apply to Enbridge’s separate proposal to build a tunnel beneath the Straits of Mackinac, which remains under review by state and federal regulators.

Similar permits issued the same day by Trump also cover several Enbridge pipeline operations in North Dakota, part of a wider effort to streamline energy infrastructure between the U.S. and Canada.

In the White House order, the administration said the permit authorizes the transport of crude oil and petroleum products across the border and requires the company to comply with all applicable federal, state and local regulations. It also mandates that the pipeline be maintained in “good repair” and holds the company responsible for environmental damages tied to its operation.

Sean McBrearty, coordinator for the environmental advocacy group Oil & Water Don’t Mix, said the move benefits Enbridge without addressing consumer costs or environmental risks. 

“Calling this ‘energy relief’ is a smokescreen. This permit won’t lower prices by a single cent. It’s a subsidy for Enbridge and paid for with continued Great Lakes risk,” McBrearty said.

Enbridge, meanwhile, welcomed the permit authorization.

“This important action enables Enbridge’s existing cross-border pipeline network, moving more than 3 million barrels a day, to continue safely and reliably delivering the energy that is foundational to both U.S. and Canadian economic competitiveness and security,” Enbridge spokesperson Ryan Duffy said.  

The Line 5 pipeline, built in 1953, stretches from northwestern Wisconsin through Michigan into Sarnia, Ontario, carrying 540,000 barrels of light crude oil, light synthetic crude and natural gas liquids a day.

The permit comes as legal disputes continue over Michigan’s attempt to shut down the pipeline and as tribal nations press treaty-based claims against the project.

McBrearty argues the administration’s action is part of a broader strategy to expand fossil fuel infrastructure.

“This is a political decision, not an energy solution,” McBrearty said. “Trump’s pipeline won’t lower gas prices. It won’t protect the Great Lakes. It will pad Enbridge’s bottom line and leave Michigan holding the risk.”