U.S. Supreme Court To Hear Arguments On Whether Line 5 Case Will Proceed In State Court

Michigan Advance

February 23, 2026

On Tuesday, the United States Supreme Court will hear arguments on whether Michigan Attorney General Dana Nessel’s case against Canadian pipeline company Enbridge should continue in state court, or be heard in federal court.

Nessel first brought a suit against Enbridge in 2019, seeking to shut down the company’s Line 5 pipeline, which runs through the environmentally sensitive Straits of Mackinac. After more than a year of litigation, Enbridge filed a successful motion to move from state court to the U.S. District Court for the Western District of Michigan.

While Nessel later secured a ruling in the Sixth Circuit Court of Appeals sending the case back to state court, Enbridge requested the U.S. Supreme Court review the lower court’s decision.

The attorney general has long argued “this is a Michigan case brought under Michigan law that the People of Michigan and its courts should rightly decide,” while Enbridge has argued that the federal government holds exclusive authority over pipeline safety matters, and that a shutdown of Line 5 would violate the 1977 transit pipeline’s treaty between the U.S. and Canada.

Michigan’s Tribal Nations and environmental advocates have consistently warned of the catastrophic risks associated with operating a pipeline in the Great Lakes, with a 2016 study from the University of Michigan finding that more than 700 miles of shoreline are at risk of pollution should Line 5 rupture.

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