WASHINGTON — The U.S. Supreme Court ruled unanimously Wednesday that Michigan’s legal effort to shutter Enbridge Energy’s Line 5 pipeline must proceed in state court, dealing a procedural blow to the Calgary-based energy firm.
Writing for the Court, Justice Sonia Sotomayor stated that Enbridge “waited too long” to move the litigation into the federal system. The decision leaves intact a lower-court ruling, effectively clearing the path for Michigan judges to determine the fate of the controversial 4.5-mile pipeline segment running beneath the Straits of Mackinac.
A Jurisdictional Defeat
The ruling centers on a 2019 lawsuit filed by Michigan Attorney General Dana Nessel. Nessel sought to void the easement allowing Enbridge to operate the pipeline, which transports crude oil and natural gas liquids between Wisconsin and Ontario. She argued the 71-year-old infrastructure poses an “unacceptable risk” to the Great Lakes.
Enbridge attempted to move the case to federal court in 2021, claiming the dispute involved cross-border energy interests. However, the 6th U.S. Circuit Court of Appeals ruled in June 2024 that the company missed a mandatory 30-day deadline to change jurisdictions. The Supreme Court’s Wednesday decision upholds that finding.
Environmental Stakes and Energy Security
Line 5 has faced intense scrutiny since Enbridge disclosed gaps in the pipeline’s protective coating in 2014. Tensions escalated in 2018 when a ship’s anchor struck the underwater section, narrowly avoiding a spill in the world’s largest freshwater system.
While Michigan officials demand a total shutdown to protect the environment, Enbridge maintains the line is critical for regional energy supplies. In a statement following the ruling, Enbridge dismissed the decision as “procedural” and reaffirmed its commitment to safe operations.
Parallel Legal Battles
The Supreme Court ruling does not end the conflict. Enbridge is currently engaged in several other legal fronts, including:
- The Tunnel Project: A federal case regarding Governor Gretchen Whitmer’s 2020 attempt to revoke the pipeline’s easement. Enbridge proposes encasing the pipes in a protective concrete tunnel, a project awaiting final federal approval.
- The Wisconsin Dispute: A separate federal challenge in Wisconsin, where a judge ordered a shutdown of a segment crossing tribal land.
Unanimity on Procedure
Despite the Court’s frequent ideological splits, unanimous rulings remain common in cases involving technical statutory interpretations and procedural deadlines. Data from the 2024-2025 term indicates that approximately 42% of the Court’s opinions were decided unanimously, often in cases where justices prioritize jurisdictional clarity over broader constitutional debates.
The case now returns to Ingham County, where a state judge will decide if Michigan has the authority to permanently halt the flow of oil through the Straits.
