The U.S. Supreme Court unanimously rejected a bid by Enbridge Inc. to move a high-stakes environmental lawsuit over its Line 5 oil pipeline from state to federal court, handing a procedural victory to the state of Michigan.

The justices ruled that the Calgary-based energy company waited far too long to seek the venue change. Federal law typically requires defendants to request such a move within 30 days, but Enbridge waited 887 days before attempting to shift the case.

Writing for the court, Justice Sonia Sotomayor stated that allowing such a delay would "undermine Congress’s manifest interest in resolving threshold removal questions early and conclusively." 

She noted that a ruling in favor of Enbridge would create "uncertainty and risk significant waste of resources" if cases could be moved years into litigation.

The dispute centers on Line 5, a 645-mile pipeline that carries 540,000 barrels of crude oil and refined products daily from Superior, Wisconsin, to Sarnia, Ontario. 

At the heart of the legal battle is a four-mile section of the aging pipe that runs along the lakebed of the Straits of Mackinac, connecting Lake Michigan and Lake Huron.

Michigan Attorney General Dana Nessel filed the suit in 2019, arguing the pipeline’s continued operation violates state public nuisance and environmental laws. 

Nessel and other state officials, including Gov. Gretchen Whitmer, have sought to shut down the underwater segment, citing the catastrophic risk of an oil leak in the Great Lakes.

In a statement Wednesday, Nessel said the ruling "makes emphatically clear that our lawsuit against Enbridge belongs before the state court."

Enbridge, which views federal court as a more favorable venue for its defense, characterized the decision as "procedural." 

The company added it remains committed to the safe operation of the line and "working constructively with regulators and stakeholders."

While the ruling settles the venue for this specific suit, other legal battles over Line 5 remain active in the federal system, including the state’s ongoing efforts to revoke a 1953 easement that allows the pipeline to occupy the Straits.