WASHINGTON (AP) — The Supreme Court on Wednesday sided with Michigan in ruling that the state’s lawsuit seeking to shut down a section of an aging pipeline beneath a Great Lakes channel will stay in state court.

Justice Sonia Sotomayor wrote for a unanimous court that the Enbridge energy company waited too long to try to move the case to federal court.

The case is part of a messy legal dispute about a pipeline that has moved crude oil and natural gas liquids between Superior, Wisconsin, and Sarnia, Ontario, since 1953.

Michigan Attorney General Dana Nessel sued in state court in June 2019 seeking to void the easement that allows Enbridge to operate a 4.5-mile section of pipeline under the Straits of Mackinac, which link Lake Michigan and Lake Huron. Nessel, a Democrat, won a restraining order shutting down the pipeline from Ingham County Judge James Jamo in June 2020, although Enbridge was allowed to continue operations after meeting safety requirements.

Enbridge moved the lawsuit into federal court in 2021, arguing it affects U.S. and Canadian trade. But a three-judge panel from the 6th U.S. Circuit Court of Appeals sent the case back to Jamo in June 2024, finding that the company missed a 30-day deadline to change jurisdictions.

The pipeline at issue is called Line 5. Concerns over the section beneath the straits rupturing and causing a catastrophic spill have been growing since 2017, when Enbridge engineers revealed they had known about gaps in the section’s protective coating since 2014. A boat anchor damaged the section in 2018, intensifying fears of a spill.

The Michigan Department of Natural Resources under Gov. Gretchen Whitmer revoked the straits easement for Line 5 in 2020. Enbridge filed a separate federal lawsuit challenging the revocation.

Enbridge won a ruling from a federal judge blocking the move, but Whitmer, a Democrat, has appealed to the 6th U.S. Circuit Court of Appeals. In March, the Supreme Court rejected Whitmer’s appeal claiming that she couldn’t be sued in federal court.

It was unclear how the federal ruling blocking Whitmer’s revocation attempt would affect Nessel’s case in state court. The company said in a statement that the judge in the Whitmer case has already decided federal regulators, not the state, are responsible for Line 5 safety and they have found no issues that would warrant shutting it down.