What began as a straightforward question from one water-quality advocate has morphed into a high-stakes battle over an oil pipeline at the highest levels of the U.S. government – with implications that go far beyond the fate of a technical legal conflict.

The question arose after a 2010 Enbridge Energy oil spill in Michigan. The advocate asked what other Michigan waterways were at risk from crude oil spills. But in the wake of, among other issues, two ships doing damage to an underwater section of another Enbridge oil pipeline, the conflict has now come all the way to the U.S. Supreme Court.

On Feb. 24, 2026, the justices will hear oral arguments and thereafter deliberate about the future of Enbridge Energy’s Line 5 oil pipeline, which runs through Michigan and Wisconsin.

As a water policy scholar with a focus on the Great Lakes, I have participated directly in the Line 5 debate as a gubernatorial appointee to an advisory board, as well as analyzed its implications. I see this moment in the Supreme Court as one layer of a complex debate that Line 5 has stirred up about states’ rights, Indigenous rights and the future of the fossil fuel economy.

Enbridge Energy vs. Dana Nessel

The actual issue in front of the Supreme Court is procedural: In 2019, Michigan Attorney General Dana Nessel sued Enbridge in a Michigan state court, seeking to shut down the pipeline, alleging “violations of the public-trust doctrine, common-law public nuisance, and the Michigan Environmental Protection Act.” Federal law allowed Enbridge to seek to move the case to federal court within 30 days of the initial filing.

Enbridge did not do so, but the Canada-based multinational company has since argued that it still should be allowed to deal with the case in federal court, as it is doing in a similar case brought by Michigan Gov. Gretchen Whitmer in 2020.

The specific question before the Supreme Court is a very technical legal one: Even though........

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