Sonia Sotomayor Pens Unanimous Supreme Court Opinion in Michigan's Favor
Justice Sonia Sotomayor wrote for a unanimous Supreme Court on Wednesday in a ruling that keeps Michigan's lawsuit seeking to shut down a portion of an aging Great Lakes pipeline in state court, dealing a setback to Canadian energy company Enbridge.
The court said Enbridge waited too long to try to move the case into federal court, rejecting the company's argument that the dispute belongs there because it implicates U.S. and Canadian trade. Sotomayor said federal law imposes a strict deadline for such jurisdictional moves, one Enbridge missed.
"Enbridge waited too long to remove this case to federal court,” Sotomayor wrote.
The decision leaves intact a lower-court ruling that returned the case to a Michigan judge and allows the state's lawsuit to continue in state court as it seeks to block operation of a key segment of Line 5, a petroleum pipeline that has transported crude oil and natural gas liquids between Superior, Wisconsin, and Sarnia, Ontario, since 1953.
What Is Line 5 and Why Michigan Wants It Shut Down
Michigan Attorney General Dana Nessel filed the lawsuit in June 2019, asking a state court to void the easement that allows Enbridge to operate a roughly 4.5-mile section of Line 5 beneath the Straits of Mackinac, the waterway connecting Lake Michigan and Lake Huron. Nessel, a Democrat, argued the pipeline poses an unacceptable risk to the Great Lakes.
An Ingham County judge issued a restraining order in June 2020 ordering the pipeline shut down, though Enbridge was permitted to continue operating after meeting certain safety requirements.
Enbridge sought to move the case to federal court in 2021, contending the dispute raised federal issues involving cross‑border energy transportation. But in June 2024, a three-judge panel of the 6th U.S. Circuit Court of Appeals ruled that Enbridge missed a 30‑day deadline to change jurisdictions, sending the case back to state court. The Supreme Court agreed.
Concerns about Line 5 have intensified in recent years after Enbridge disclosed that it had been aware of gaps in the pipeline's protective coating beneath the straits since at least 2014. In 2018, a ship's anchor struck the underwater section, heightening fears of a potential spill in one of the world's largest freshwater systems.
Separately, Michigan Democratic Governor Gretchen Whitmer's administration revoked the pipeline's easement in 2020. Enbridge is challenging that action in federal court and has proposed encasing the underwater portion of Line 5 in a protective tunnel. State regulators approved permits for the tunnel in 2023, but key federal approvals are still pending.
Line 5 is also the subject of litigation in Wisconsin, where a federal judge has ordered Enbridge to shut down a segment of the pipeline running through tribal land unless it can be rerouted. The company has appealed that ruling.
Supreme Court Unanimous Rulings: What to Know
Despite the Supreme Court's sharp ideological divisions in many high‑profile cases, unanimous rulings are relatively common. According to SCOTUSblog's end‑of‑term Stat Pack released in June 2025, covering the October 2024 term, about 42% of the court's opinions were decided unanimously.
Such outcomes are especially frequent in cases involving procedural deadlines, jurisdictional rules or technical questions of statutory interpretation, court watchers say-areas where justices often agree even as they remain divided on broader constitutional issues.
This is a breaking news article. Updates to follow.
Reporting by the Associated Press contributed to this article.
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This story was originally published April 22, 2026 at 10:26 AM.