Michigan Supreme Court rejects permit for Enbridge oil pipeline under Great Lakes

What This is

• The Michigan Supreme Court ordered a new review of a state permit that allowed Enbridge to build a tunnel for its Line 5 oil pipeline under the Straits of Mackinac in the Great Lakes.
• The court said regulators did not properly consider whether the tunnel would extend how long Line 5 operates and did not adequately assess other options and the state’s public-trust duties to protect Great Lakes waters.
• Four tribal nations and environmental groups challenged the 2023 permit, arguing the project threatens the Great Lakes and would harm culturally important sites.
• Michigan agencies had previously issued key permits for the proposed tunnel even while acknowledging “significant impacts” to wetlands, rare species, and Native American burial grounds.
• Supporters of the tunnel argue it would reduce the risk of an oil spill compared with the current pipeline segment in the Straits.
• Enbridge is also facing Line 5 legal trouble in Wisconsin, where a federal appeals court found the pipeline trespassed on the Bad River Band’s reservation and ordered the company to remove and reroute it, with extra time to comply.

Why This Matters

• The decision affects how strongly Michigan must protect shared Great Lakes waters when approving major industrial projects.
• It shapes how state agencies weigh energy infrastructure needs against spill risk, wetlands damage, and other environmental harms.
• Tribal governments’ treaty rights and protection of sacred and burial sites are central to whether projects can proceed.
• The outcome could influence oil and fuel transport options in the region if Line 5 faces delays or reroutes.