Katherine Dailey/Michigan Advance. The U.S. Supreme Court’s front steps in Washington, D.C. July 19, 2022.

WASHINGTON — 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.