The U.S. Supreme Court heard arguments on whether the controversial Line 5 pipeline case belongs in state or federal court. Michigan Attorney General Dana Nessel seeks to shut down the pipeline due to risks to the Great Lakes, while Enbridge Energy argues for federal oversight. The procedural dispute could affect the pipeline's operation across the Straits of Mackinac.
The U.S. Supreme Court convened on February 24, 2026, to address a jurisdictional question surrounding the Line 5 pipeline, which has transported crude oil and natural gas liquids 645 miles from Superior, Wisconsin, to Sarnia, Ontario, since 1953. A key 4.5-mile segment runs along the bottom of the Straits of Mackinac between Lakes Huron and Michigan.
Michigan Attorney General Dana Nessel filed a lawsuit in 2019 to revoke the easement allowing the pipeline to cross the Straits, citing environmental risks. Over its 73-year history, Line 5 has spilled more than a million gallons of oil along its route. The effort to shut it down garners support from all 12 federally recognized tribes in Michigan, who highlight threats to their waters, treaty rights, and communities.
The core issue before the justices is whether Enbridge Energy missed a 30-day deadline to transfer the case from state to federal court. Enbridge, a Canadian company, contends federal court is appropriate for matters involving pipeline safety regulations and international agreements, as Line 5 supplies half the oil for Ontario and Quebec. Nessel maintains the case pertains to state laws on public natural resources, emphasizing potential environmental, economic, and health impacts from a spill in the Great Lakes.
During arguments, Justice Samuel Alito noted, “If this proceeds in state court, and the state court issues a preliminary injunction against continued operation of the pipeline, it could be a long time before this issue involving treaty rights, which is a federal question, could be reviewed here.” Enbridge lawyer John Bursch argued the deadline resembles a statute of limitations and exceptional circumstances warrant flexibility, stating, “I don’t think it was clear to anyone that there was necessarily federal jurisdiction at the outset of the state court case.” Representing the state, Ann Sherman countered that the deadline is rigid, adding, “Enbridge seeks an atextual escape hatch.”
Enbridge spokesperson Ryan Duffy warned of “significant implications for energy security and foreign affairs” if the case remains in state court. The company first sought federal jurisdiction in 2021; a federal district court initially sided with Enbridge, but the U.S. Sixth Circuit Court of Appeals ruled for Michigan.
A ruling is anticipated before the court's summer term. University of Michigan Law School lecturer Andy Buchsbaum explained that a decision favoring Michigan would send the case to state court, while flexibility on the deadline could prompt further review. Bay Mills Indian Community President Whitney Gravelle expressed concern post-arguments: “Line 5 continues to remain a clear and present danger to the Great Lakes and every tribal nation in every community that relies on them.”
Meanwhile, Enbridge advances plans for a tunnel to replace the Straits segment, pending permits. Next month, the Michigan Supreme Court will review a related challenge from tribes and environmental groups. For Love of Water Executive Director Liz Kirkwood urged a shift from fossil fuels: “We should be thinking about the future and the transition away from fossil fuel. And move towards a future that is sustainable and more equitable.”
