At the end of its term late last month, the Michigan Supreme Court issued an opinion in In re Application of Enbridge Energy to Replace and Relocate Line 5, ___ Mich ___ (Docket Nos. 168335 et al.) (2026). The Court vacated an order from the Michigan Public Service Commission (“MPSC”) approving the proposed replacement of Enbridge’s Line 5 pipeline across the Straits of Mackinac with a below-lakebed tunnel and remanded the case to the MPSC. Although much of the opinion is specific to the Line 5 project, the Court’s holding with respect to the public trust doctrine is likely to have broader implications, particularly for municipalities and property owners along the Great Lakes.
The public trust doctrine recognizes that the Great Lakes and the bottomlands beneath them exist for the benefit of the public. Under the doctrine, the State has a responsibility to protect and preserve both the Great Lakes and their bottomlands so that the public can use them for activities including fishing, hunting, navigation, boating, and walking along portions of the lakeshore.
In this recent opinion, the Court clarified that the Michigan Legislature incorporated the public trust doctrine when it created the Michigan Environmental Protection Act (“MEPA”), MCL 324.1701 et seq. As a result, when courts or agencies review a proposed project under MEPA, they must consider the public trust doctrine when evaluating the project’s environmental impacts. Going forward, projects along the Great Lakes that may impact the public’s rights under the public trust doctrine—even if indirectly, such as through an increased risk of pollution or other environmental harm—may face additional scrutiny.