Michigan's highest court ruled 6-1 that state regulators botched the permitting process for a proposed tunnel to carry the Enbridge Line 5 oil pipeline under the Great Lakes, sending the project back to square one after nearly a decade of review.

The Michigan Supreme Court on Friday ordered the Michigan Public Service Commission to reconsider the 2023 permit it granted for a tunnel beneath the Straits of Mackinac, where Lakes Huron and Michigan meet. The court found three distinct failures in the commission's work: regulators never assessed whether the tunnel would extend the 73-year-old pipeline's operational lifetime and thereby increase environmental harm, they applied inconsistent standards when comparing alternatives like trucks and trains, and they neglected to evaluate the tunnel's impact on fishing, boating, and other public trust rights on the Great Lakes.

Only one justice dissented. The ruling does not kill the tunnel outright, but it forces the commission to reopen its analysis, adding yet another layer of delay to a project that Enbridge says has already spent close to a decade winding through regulatory and legal channels.

A 73-year-old pipeline caught between regulators and courts

Line 5 runs from Superior, Wisconsin, to Sarnia, Ontario, carrying more than half a million barrels of oil per day. A four-mile stretch of the pipeline sits on the bottom of the Straits of Mackinac. Roughly a decade ago, a ship anchor dented part of that underwater section, and Enbridge proposed encasing the pipeline in a concrete tunnel beneath the lakebed as a long-term fix.

The Michigan Public Service Commission approved the tunnel permit in 2023. Four tribal nations and several environmental groups promptly sued. The Washington Examiner reported that the tribal plaintiffs include the Bay Mills Indian Community, Little Traverse Bay Bands of Odawa Indians, Grand Traverse Band of Ottawa and Chippewa Indians, and Nottawaseppi Huron Band of the Potawatomi. They were joined by environmental organizations including Earthjustice.

The case wound its way to the state Supreme Court, which agreed to hear the challenge. Friday's ruling landed squarely against the commission.

Enbridge spokesman Ryan Duffy said the company is reviewing its legal options. In a statement reported by CBS News, Duffy called the ruling:

"Disappointed for another delay in a project that has been under review for nearly a decade" that would "enhance environmental protection of the Great Lakes while maintaining critical energy reliability for the region."

That frustration is understandable. Enbridge proposed the tunnel specifically to address environmental concerns about the aging underwater pipeline. The company's argument, that encasing the line in concrete is safer than leaving it exposed on the lake bottom, has a common-sense appeal that the court's ruling does not directly refute. The court did not say the tunnel is a bad idea. It said the commission did not do its homework.

Whitmer has wanted Line 5 gone since 2020

The tunnel permit fight is only one front in a broader legal campaign against Line 5. Governor Gretchen Whitmer and other state officials have been trying since 2020 to shut down the pipeline's underwater section entirely. Those efforts involve a separate set of court cases that remain unresolved.

Whitmer's position, that the pipeline should be moved away from the waterway altogether, puts her at odds not only with Enbridge but with the energy infrastructure that serves the broader Great Lakes region. The pipeline has operated for more than seven decades. Shutting it down without a viable replacement would raise serious questions about energy reliability for homes and businesses across the upper Midwest, a concern courts have grappled with in other high-profile rulings involving the tension between regulatory mandates and practical consequences.

Opponents of Line 5 frame the issue in environmental and cultural terms. David Gover, an attorney with the Native American Rights Fund, issued a statement after the ruling:

"Whether Line 5 is suspended in the water or encased in a tunnel, it is simply a terrible idea to pump more than half a million barrels of oil every day through the middle of the Great Lakes."

Opponents also note that the Straits of Mackinac is considered a sacred site by the Anishinaabe tribes. That cultural claim adds political weight to the legal challenge, even if it played no explicit role in the court's three-part finding against the commission.

Trump's energy emergency order adds a federal wrinkle

The tunnel project carries significance beyond Michigan's borders. The Washington Examiner reported that the seven-year construction project was being expedited under President Trump's day-one executive order declaring a national energy emergency. No ground has been broken, however, and Friday's ruling ensures that construction remains on hold while the commission revisits its analysis.

The federal push to accelerate energy infrastructure sits in direct tension with the state-level regulatory and legal obstacles that have kept Line 5's tunnel in limbo. That tension mirrors broader conflicts playing out across the country, where federal priorities and state-level resistance collide on everything from energy policy to national security.

Earthjustice senior associate attorney Adam Ratchenski framed the stakes in sweeping terms, saying the court's decision "will have significant consequences for the protection of the Great Lakes and all of Michigan's natural resources including tribal resources."

Three failures the commission must now fix

The court's ruling identified specific analytical gaps the commission must address on remand. First, the commission never examined whether placing Line 5 inside a tunnel would effectively guarantee the pipeline operates for decades longer than it otherwise would, and whether that extended lifetime would produce additional environmental harm. For a pipeline already 73 years old, that is not a trivial omission.

Second, the commission applied inconsistent standards when it weighed alternatives. Moving oil by truck or rail, for example, was evaluated under different assumptions than the tunnel option, making the comparison unreliable. Third, the commission failed to assess the tunnel's potential impact on public trust rights, the legal doctrine that the state holds navigable waters and their beds in trust for the public's right to fish, boat, and use the resource.

Each of those failures, standing alone, might have been enough to send the permit back. Together, they paint a picture of a regulatory process that moved forward without answering basic questions. That is the kind of sloppy government work that invites litigation, and the commission now has to do the job it should have done the first time.

The broader pattern is familiar. When agencies cut corners on permitting, the result is not faster infrastructure, it is longer delays, more lawsuits, and more uncertainty for the companies and communities waiting for a decision. The same dynamic has played out in contentious Senate confirmation battles and in courtrooms across the country, where procedural failures hand opponents the tools to block projects that might otherwise survive on the merits.

What happens next remains unclear

Several questions remain unanswered. The ruling does not specify whether the existing permit is suspended during the reconsideration or whether Enbridge could proceed with any preliminary work. The current operational status of the underwater pipeline section, whether oil is still flowing through the exposed stretch on the lake bottom, is not addressed in the court's decision as reported. And the separate legal campaign by Whitmer's administration to shut down Line 5 entirely continues in parallel, meaning Enbridge faces the possibility of winning a reconsidered tunnel permit only to have the pipeline itself ordered closed.

The Associated Press reported that the ruling further jeopardizes the future of both the pipeline and the proposed tunnel project. Enbridge said it is reviewing its options, but the company offered no specifics on what legal avenues remain.

For the people who depend on Line 5's energy, and for the taxpayers and ratepayers who will ultimately bear the cost of whatever comes next, the court's decision means more waiting. The pipeline is 73 years old. The tunnel was proposed roughly a decade ago. The permit was granted three years ago. And now the process starts over, because regulators could not be bothered to answer the right questions the first time.

When the government cannot get the basics of a permit review right, the people who pay the price are never the bureaucrats. They are the families whose energy bills depend on infrastructure that politicians and regulators keep tangling in red tape, while the pipeline sits on the lake bottom, and the clock keeps ticking.