Michigan Supreme Court to Decide Fate of Line 5 Tunnel Permit as Pipeline Controversy Continues
LANSING — The Michigan Supreme Court is poised to make a crucial ruling on whether state regulators properly approved a tunnel project for Enbridge's controversial Line 5 oil pipeline through the Straits of Mackinac.
The case reaches the state's highest court after environmental groups and tribal nations challenged a key permit issued by the Michigan Public Service Commission. The commission approved Enbridge's proposal in December 2023 to reroute a four-mile segment of the pipeline into a tunnel beneath the straits, moving it from open water into a protected tunnel beneath the lake bed.
Legal Battle Over Environmental Review
David Scott, an attorney for environmental groups challenging the permit, argued before Michigan justices that state energy regulators issued the tunnel permit based on what he called a "lopsided analysis that needs to be corrected." He asked the court to order a more thorough review of the plan to encase the petroleum pipeline into a tunnel buried beneath the Straits of Mackinac.
Enbridge lawyer John Bursch, meanwhile, argued that state regulators correctly concluded the tunnel is the safest option for a pipeline that will keep operating one way or another. Where do you want the pipeline, Bursch asked. Do you want it in the tunnel or do you want it operating in the water.
Tribal Nations and Environmental Groups Sue
The case stems from the Michigan Public Service Commission's December 2023 approval of Enbridge's proposal to reroute a four-mile segment of the controversial petroleum pipeline out of the open water and into a tunnel. That decision prompted outcry from pipeline opponents, who have argued the 72-year-old pipeline should be shut down rather than merely rerouted.
A coalition of four Michigan tribal nations joined by the Environmental Law and Policy Center and the Michigan Climate Action Network responded with two separate lawsuits, triggering a legal dispute that reached Michigan's highest court after the Michigan Court of Appeals sided with the state.
The tribes — the Bay Mills Indian Community, Grand Traverse Band of Ottawa and Chippewa Indians, Little Traverse Bay Band of Odawa Indians and Nottawaseppi Huron Band of the Potawatomi, joined by the Environmental Law and Policy Center and the Michigan Climate Action Network, argue the commission should have considered possible environmental impacts such as oil spill risks along the length of the 645-mile pipeline.
Traverse City-based Flow Water Advocates, meanwhile, argues the commission inadequately considered the tunnel project's impact on the Great Lakes as a public trust resource. Michigan's public trust doctrine says the state holds resources like the Great Lakes and bottomlands in trust for the people.
Pipeline Stays Open Either Way
Bursch's argument that the pipeline will run one way or another rested on the assumption that Enbridge will win a separate legal dispute with state officials who have ordered the pipeline shut down for fear it could rupture and cause a catastrophic Great Lakes oil spill.
But some justices appeared skeptical. Is there a final determination on that point yet, Chief Justice Megan Cavanagh asked Bursch. The answer is not yet. While U.S. District Court Judge Robert Jonker ruled in December that federal pipeline safety law leaves Michigan no authority to order a shutdown, the state is appealing the decision.
Ongoing Legal and Regulatory Battles
The Michigan Supreme Court case argued Wednesday is one of several ongoing regulatory and judicial deliberations that could seal the fate of the controversial pipeline. In addition to the federal appeals case, Enbridge and Michigan are awaiting a key U.S. Supreme Court decision tied to Michigan Attorney General Dana Nessel's attempt to shut down the pipeline.
Meanwhile, the state and federal government are considering whether to issue other permits for the tunnel project.
When Scott argued that Enbridge's request to reroute Line 5 should have triggered a broad state review of the entire pipeline's environmental impacts, Justice Elizabeth Welch expressed concern about setting a precedent for prolonged reviews of other, more routine utility reroutes. Where do we draw the line, she asked.
When Enbridge lawyer Bursch began to warn about the potential economic implications of shutting down the pipeline, Justice Richard Bernstein interjected, What would you say are the real-life implications if there were a spill.
Decade-Long Dispute
Lawyers for both sides accused their opponents of using the courts to needlessly delay the final outcome of a now decade-long dispute over the fate of Line 5.
Amid mounting calls to shut down the lakebottom pipeline lest it cause an oil spill in the Straits, Enbridge hatched a deal in 2018 with the administration of then-Gov. Rick Snyder to build the tunnel project, estimating at the time the project would cost 500 million and be complete in 2024. But groundbreaking has yet to begin as Enbridge awaits multiple permitting decisions and navigates legal disputes with those who favor a shutdown.
At the end of Wednesday's nearly two-hour proceedings, justices gave no indication of their timeline for making a decision in the case. The court's current term ends July 31.
Broader Line 5 Legal Battles
The U.S. Supreme Court has rejected an appeal from the state of Michigan that argues Gov. Gretchen Whitmer has sovereign immunity from a lawsuit filed by Enbridge Energy to maintain operations of the Line 5 oil pipeline.
The justices on Tuesday denied the state's petition for a writ of certiorari, meaning they will not weigh in on the appeal filed by the state. We are disappointed by the Supreme Court's decision not to review this important issue of state sovereignty, said Danny Wimmer, a spokesman for Attorney General Dana Nessel's office. We will continue to fight for the people of Michigan on these vital issues concerning the Line 5 pipelines in the Straits.
Whitmer and Nessel campaigned on promises to shutter the more than 70-year-old pipeline and initiated litigation between 2019 and 2020 after negotiations to speed up the construction of a tunnel to house the line failed. In 2020, Whitmer revoked Enbridge's 1953 easement that allows the operation of the twin 20-inch underwater pipelines on the bottom of the Lake Michigan side of the Straits of Mackinac, west of the Mackinac Bridge.
That revocation prompted Enbridge to file suit in federal court seeking an order to keep the pipeline running. In late 2018, then-Gov. Rick Snyder entered into an agreement with Enbridge, in which the Calgary, Alberta-based company promised to build a tunnel under the Straits of Mackinac to house a new segment of Line 5 and protect it from potential anchor strikes or other disturbances.
Enbridge has secured most of its state permits for the tunnel, but is waiting on the completion of a federal review before it can begin construction.
State Appeals Denied by U.S. Supreme Court
The U.S. District Court in December sided with Enbridge in the case filed by the Canadian oil giant against Whitmer, ruling that federal law governing pipeline safety preempts the state's multi-year effort to shutter the line.
A separate case questioning the jurisdiction of the Line 5 legal fight is pending before the U.S. Supreme Court. The justices heard arguments in February over whether a separate lawsuit filed by Nessel seeking to shut down the pipeline was properly removed to federal court.
The seven justices in Michigan heard arguments earlier this month on a challenge to a permit Enbridge needs to build a tunnel to house a new segment of Line 5 in the straits.
The state has been in a years-long battle over the future of Line 5 as the underwater twin span running through the Straits of Mackinac has raised concerns about the potential for a catastrophic pipeline failure at the nexus of Lakes Michigan and Huron.
Sources:
- https://www.wilx.com/2026/03/31/michigan-supreme-court-weighs-line-5-pipeline-project/
- https://www.detroitnews.com/story/news/local/michigan/2026/03/31/gov-gretchen-whitmer-line-5-pipeline-enbridge-appeal-loss-u-s-supreme-court/89410352007/
- https://bridgemi.com/michigan-environment-watch/enbridge-line-5-foes-argue-tunnel-plan-before-michigan-supreme-court/