Supreme Court Unanimously Rules for Michigan in Pipeline Jurisdiction Dispute
The United States Supreme Court has delivered a significant victory for the state of Michigan, ruling unanimously that its lawsuit aiming to shut down a section of an aging energy pipeline beneath a Great Lakes channel must remain in state court. Justice Sonia Sotomayor authored the opinion, which was issued on Wednesday, 22 April 2026.
Jurisdictional Battle Over Line 5 Pipeline
The case centres on a protracted legal conflict involving the Enbridge energy company and its Line 5 pipeline, which has transported crude oil and natural gas liquids between Superior, Wisconsin, and Sarnia, Ontario, since 1953. At issue is a 4.5-mile (6.4-kilometre) segment running under the Straits of Mackinac, connecting Lake Michigan and Lake Huron.
Justice Sotomayor wrote that Enbridge waited too long in its attempt to transfer the case to federal court. The company had argued in 2021 that the lawsuit impacted U.S. and Canadian trade, warranting federal jurisdiction. However, a three-judge panel from the 6th U.S. Circuit Court of Appeals had already returned the case to state court in June 2024, finding Enbridge missed a critical 30-day deadline for changing jurisdictions.
Michigan's Legal Actions and Environmental Concerns
Michigan Attorney General Dana Nessel, a Democrat, initiated the lawsuit in state court in June 2019, seeking to void the easement that permits Enbridge to operate the pipeline section. In June 2020, Ingham County Judge James Jamo granted a restraining order to shut down the pipeline, though Enbridge was allowed to continue operations after meeting specific safety requirements.
Environmental anxieties have escalated since 2017, when Enbridge engineers disclosed knowledge of gaps in the pipeline's protective coating dating back to 2014. A boat anchor damaging the section in 2018 further heightened fears of a catastrophic spill in the ecologically sensitive Great Lakes region.
Under Democratic Governor Gretchen Whitmer, the Michigan Department of Natural Resources revoked the straits easement for Line 5 in 2020. Enbridge has filed a separate federal lawsuit challenging this revocation.
Ongoing Permitting and Broader Legal Challenges
Enbridge is pursuing permits to encase the pipeline section in a protective tunnel as a mitigation measure. The Michigan Public Service Commission approved relevant permits in 2023, but the company still requires authorisation from the U.S. Army Corps of Engineers and the Michigan Department of Environment, Great Lakes and Energy.
The legal turmoil extends beyond Michigan. In Wisconsin, a federal judge in Madison last summer ordered Enbridge to shut down part of Line 5 that crosses the Bad River Band of Lake Superior's reservation within three years. The company has proposed rerouting the pipeline around the reservation and has appealed the shutdown order to the 7th U.S. Circuit Court of Appeals.
This Supreme Court decision reinforces state-level judicial oversight in this high-stakes environmental and energy dispute, potentially influencing similar cases across the nation.
