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Environment
Apr 23, 2026
Analyzed by GPT OSS 120B

U.S. Supreme Court Backs Michigan in Fight to Shut Down Aging Line 5 Pipeline

AI Summary
The U.S. Supreme Court unanimously ruled that Michigan’s state‑court lawsuit to close a 4.5‑mile section of Enbridge’s Line 5 pipeline under the Straits of Mackinac must stay in state court, marking a victory for environmental advocates. The decision keeps the legal battle alive amid growing concerns over a potential spill in the Great Lakes.

The U.S. Supreme Court on Wednesday ruled unanimously that Michigan’s state‑court lawsuit to shut down a 4.5‑mile section of Enbridge’s Line 5 pipeline under the Straits of Mackinac will remain in state court, a win for the state’s environmental advocates.

Supreme Court Affirms State‑Court Jurisdiction Over Line 5

Justice Sonia Sotomayor wrote for the Court, stating that Enbridge missed the 30‑day deadline to move the case to federal court, so the dispute stays with Judge James Jamo in Michigan.

Key Timeline and Legal Milestones

  • June 2019: Attorney General Dana Nessel files state‑court suit to void the easement.
  • June 2020: Judge Jamo issues restraining order, temporarily shutting the pipeline.
  • 2021: Enbridge seeks federal jurisdiction, citing U.S.–Canada trade.
  • June 2024: Sixth Circuit sends case back to state court after missed deadline.
  • 2026: Supreme Court upholds state‑court path.

Regulatory and Financial Stakes of the Line 5 Controversy

Enbridge is pursuing a federal permit to encase the Straits section in a protective tunnel, a project approved by the Michigan Public Service Commission in 2023. The tunnel could cost hundreds of millions of dollars, though exact figures have not been disclosed. Simultaneously, the company faces potential shutdown costs and liability for any spill in the Great Lakes, which could run into billions.

Environmental and Cross‑Border Energy Implications

The 4.5‑mile segment carries crude oil and natural‑gas liquids that have moved through the Great Lakes corridor since 1953. A rupture could threaten the water supply for millions and damage fragile ecosystems. The case also tests the balance between U.S. energy infrastructure and Canadian trade interests.

Future Legal Landscape for Line 5

With the Supreme Court’s decision, Michigan’s state‑court battle proceeds, while parallel federal challenges over the tunnel and the Bad River Band shutdown continue. Analysts expect further appeals to the Sixth and Seventh Circuits, and possible legislative action from Congress on pipeline safety standards.