Written on: August 8, 2026
From the National Propane Gas Association Bobtail
On Friday, July 31, the Michigan Supreme Court vacated a Michigan Public Service Commission order authorizing the Line 5 pipeline in a tunnel under the Straits of Mackinac,and sent the case back to the commission for further review under the Michigan Environmental Protection Act. In a 6-1 decision, the majority said the commission should have considered whether building the tunnel would effectively extend the life of the Line 5 pipeline and, in turn, lead to additional environmental harm. The court also found fault with the commission’s analysis of alternatives to the project and said regulators failed to consider potential impacts on public trust resources protected under Michigan law.
The Court found the review too narrow: regulators never examined whether the tunnel would extend Line 5’s lifetime, compared alternatives inconsistently, and didn’t assess impacts on fishing, boating, and other public trust rights. NPGA and MPGA intervened below in support of the project.
The decision reverses a ruling by the Michigan Court of Appeals, which had upheld the Public Service Commission’s analysis using a more deferential standard of review.
Enbridge’s spokesman stated that it is reviewing its legal options and said it is disappointed by another delay in a project already under review for nearly a decade.
Questions? Contact Director of Regulatory Affairs and Associate General Counsel Kate Gaziano at kgaziano@npga.org.
