The Supreme Court on Wednesday kept Michigan’s lawsuit over a section of the aging Line 5 pipeline in state court, rejecting an oil company’s bid to move the fight to federal court. Justice Sonia Sotomayor wrote for a unanimous court that Enbridge waited too long to try to shift the case.
The ruling leaves Dana Nessel’s challenge to a 4.5-mile section of pipeline under the Straits of Mackinac in the hands of a state judge, where it has been contested for years. Nessel sued in June 2019, seeking to void the easement that lets Enbridge operate the line beneath the channel linking Lake Michigan and Lake Huron. A year later, Ingham County Judge James Jamo issued a restraining order shutting the pipeline down, though Enbridge was allowed to keep operating after meeting safety requirements.
The pipeline has carried crude oil and natural gas liquids between Superior, Wisconsin, and Sarnia, Ontario, since 1953, and the section under the straits has become one of the most closely watched pieces of energy infrastructure in the Great Lakes. Concerns about a rupture and a catastrophic spill have grown since 2017, after Enbridge engineers disclosed that they had known about gaps in the section’s protective coating since 2014. A boat anchor damaged the section in 2018, adding to the pressure on state regulators and the company.
Enbridge argued that the case belonged in federal court because it affects U.S. and Canadian trade, and it moved the lawsuit there in 2021. But a three-judge panel from the Sixth U.S. Circuit Court of Appeals sent the case back to Jamo in June 2024, finding that Enbridge missed the 30-day deadline to change jurisdictions. Sotomayor’s opinion followed the same logic, saying the company waited too long to make the move.
The decision does not end the broader fight over Line 5. Michigan’s Department of Natural Resources revoked the straits easement in 2020, and Enbridge has a separate federal lawsuit challenging that move. The company is also seeking permits to encase the straits section in a protective tunnel, a plan the Michigan Public Service Commission approved in 2023 but which still needs approval from the U.S. Army Corps of Engineers and the Michigan Department of Environment, Great Lakes and Energy. Environmental groups and Michigan tribes have separately sued to void the tunnel permits, and the state supreme court is weighing that case.
The pipeline remains tied up in another legal clash in Wisconsin, where a federal judge in Madison last summer gave Enbridge three years to shut down part of Line 5 running across the Bad River Band of Lake Superior’s reservation. Enbridge appealed that order to the Seventh U.S. Circuit Court of Appeals and started work in February to reroute the line around the reservation, while the Bad River Band and environmental groups filed a state lawsuit seeking to halt the reroute. For now, Wednesday’s ruling keeps the Michigan case where it began, and that gives state courts the next decisive say over a section of pipe that has become a test of how far an oil company can go to keep a 1953 route alive.
