U.S. Supreme Court Hears Procedural Case With Far-Reaching Implications for Michigan Pipeline and Indigenous Rights

The U.S. Supreme Court has recently concluded oral arguments in a case concerning Enbridge Energy’s Line 5 oil pipeline, a legal dispute that originated in Michigan and now presents potential consequences extending well beyond the immediate procedural question before the court. The case stems from longstanding concerns regarding the environmental risks posed by the pipeline’s route, as well as broader questions about state sovereignty, Indigenous rights, and the future of fossil fuel infrastructure in North America.

The origins of the current legal contest can be traced to increased public scrutiny following the 2010 Enbridge oil spill in Michigan, which prompted concerns about the vulnerability of Michigan’s waterways to crude oil contamination. These anxieties were heightened by subsequent incidents, including a 2018 event in which a ship’s anchor struck the underwater section of Line 5 at the Straits of Mackinac, and a 2020 incident where another vessel damaged a pipeline support. While no crude oil was spilled in 2018—only some unspecified fluid entered the lake—the underlying risk to the Great Lakes ecosystem became a focal point for debate.

Line 5, operated by Canada-based Enbridge, transports primarily Canadian oil to Canadian refineries, traversing Michigan and the Great Lakes as a geographic shortcut. The pipeline’s crossing at the Straits of Mackinac, which connects Lakes Michigan and Huron, falls squarely within Michigan’s territorial boundaries, making it subject to state scrutiny and regulation. In 2019, Michigan Attorney General Dana Nessel filed suit in state court seeking to shut down Line 5, alleging violations of the public trust doctrine, common-law public nuisance, and the Michigan Environmental Protection Act. Under federal law, Enbridge had a 30-day window to request removal of the case to federal court but did not do so within that period. Enbridge has since argued that it should still be permitted to transfer the case to federal jurisdiction, as it did in a similar suit brought by Michigan Governor Gretchen Whitmer in 2020.

The Supreme Court’s review is narrowly focused on whether Enbridge’s failure to timely request transfer to federal court should preclude it from doing so at a later stage. Despite the technical nature of this legal question, parties on all sides acknowledge that the decision will have broader significance, potentially shaping the balance of state authority to regulate environmental risks posed by interstate and international infrastructure projects.

Parallel to the Michigan litigation, Enbridge faces a distinct challenge in Wisconsin, where Line 5 crosses the reservation of the Bad River Band of Lake Superior Chippewa. After the Band revoked Enbridge’s easement in 2013 and subsequent negotiations failed, the Band sued the company in federal court in 2019. In 2023, U.S. District Judge William Conley determined that Enbridge had been trespassing for a decade and ordered the company to pay US$3 million in damages. The court set a deadline of June 2026 for Enbridge to either reroute the pipeline around the reservation or cease operations. Both Enbridge and the Bad River Band are appealing this decision, and the outcome remains uncertain as the deadline approaches.

The Bad River case highlights deeper questions regarding Indigenous sovereignty over reservation lands and the extent of tribal self-determination in the face of large-scale energy infrastructure. Some observers contend that a victory for Enbridge could limit the ability of Indigenous nations to control major projects on their territories, potentially setting a precedent with implications for other pipeline and resource disputes across the United States.

In response to mounting legal and political challenges, Enbridge has pursued a dual strategy: contesting the cases in court while simultaneously seeking to reroute problematic sections of Line 5. In Michigan, the company has proposed relocating the pipeline into a tunnel beneath Lake Michigan, a plan requiring both federal and state permits. The Michigan Public Service Commission has authorized construction of the tunnel, but the decision is under review in the Michigan Supreme Court, and the issuance of additional state permits remains under intense scrutiny from advocacy groups and political leaders.

A similar situation exists in Wisconsin, where Enbridge has obtained federal permits to reroute Line 5 outside the Bad River Band reservation, though not beyond the watershed that serves the Band’s lands. These permits were granted in October 2025, but state-level permissions remain subject to ongoing legal and political disputes.

Environmental advocates have urged decision-makers to consider not just the immediate ecological impacts of pipeline construction and operation, but also the broader consequences for climate change, public health, and the long-term sustainability of fossil fuel use. Enbridge and its supporters have argued for a more limited approach, focusing on the localized environmental risks associated with pipeline rerouting or decommissioning, rather than the global debate over energy transition.

The Supreme Court’s decision, though likely to address a procedural aspect of federal and state court jurisdiction, is being closely watched as a barometer of the extent to which states can exercise regulatory authority over infrastructure projects with transnational dimensions. The ruling may also signal how Indigenous rights and environmental considerations are weighed against economic and energy security interests in future disputes.

The ongoing Line 5 controversy is situated within a broader contest over the future of fossil fuel infrastructure in the United States and Canada. While the technical questions now before the courts may appear limited, the outcomes could influence policy, political, and economic decisions across the region. As Professor Jeffrey Insko of Oakland University has observed, the debate over Line 5 encompasses not only immediate technical and legal matters, but also issues of climate policy, Indigenous rights, and visions for a sustainable future.

Federal agencies’ decisions to grant or withhold permits, as well as the outcomes of pending legal appeals, will likely determine the operational fate of Line 5 in coming years. How these intersecting layers of authority—federal, state, and tribal—are ultimately resolved will set precedents for the governance of energy infrastructure and environmental protection in North America.

As the Supreme Court prepares to issue its ruling, stakeholders from multiple sectors—including state officials, Indigenous governments, environmental groups, and the energy industry—are awaiting clarification on both the procedural and substantive questions raised by the Line 5 dispute. The ultimate resolution is expected to reverberate beyond the immediate parties, shaping future interactions between governments, industry, and civil society in matters of resource management and Indigenous sovereignty.