Trump DOJ argues Michigan Line 5 fight implicates U.S. foreign policy as Enbridge pipeline dispute widens

The U.S. Justice Department on Sept. 12 filed a brief arguing that Michigan Gov. Gretchen Whitmer’s 2020 decision revoking Enbridge’s easement to operate a segment of Line 5 under the Straits of Mackinac interfered with U.S. foreign policy. The filing, while not making the federal government a party to the case, contends that Whitmer’s move to curb the pipeline’s operation amounts to a bid to “globalize” Michigan’s regulatory reach in a way that clashes with the federal government’s goal of maintaining a steady energy flow between the United States and Canada. The brief underscores the broader legal fight over one of the Great Lakes region’s most contentious energy disputes and comes as the Trump administration has sought to assert its view on energy security and regulatory authority.

Line 5, a 4.5-mile (6.4-kilometer) segment of crude-oil conduit, runs beneath the Straits of Mackinac, a channel connecting Lake Michigan and Lake Huron, and has carried crude oil between Superior, Wisconsin, and Sarnia, Ontario, since 1953. The pipeline has long been the subject of safety and environmental concerns, intensified since 2017 when Enbridge disclosed gaps in protective coating dating to 2014. A boat anchor damaged the segment a year later, fueling fears of a potentially catastrophic spill in an environmentally sensitive area. Whitmer, a Democrat and potential 2028 presidential contender, ordered her regulators in November 2020 to revoke the easement allowing the Straits segment to operate. Enbridge filed a federal lawsuit that same year seeking to invalidate the order. The pipeline has continued to operate while litigation drags on.

The Justice Department’s filing argues that Whitmer’s revocation would disrupt the energy supply chain, raise domestic prices, and increase the leverage of malign foreign actors worldwide, outcomes that would conflict with the nation’s foreign policy goals. The department also contends that only the federal government may regulate pipeline safety, and permitting a patchwork of state rules would undermine a coherent national framework. A 1977 treaty between the United States and Canada that prohibits authorities from impeding the flow of energy through cross-border pipelines is cited by DOJ as further evidence against unilateral state action.

Whitmer’s attorneys counter that Michigan has authority under the public trust doctrine to revoke the easement as part of protecting natural resources entrusted to the state. Danny Wimmer, a spokesperson for Michigan Attorney General Dana Nessel, which is defending the revocation, said in an email that Nessel plans to file a response in October. He noted earlier filings arguing that revoking the easement does not impose or continue any safety regulations and is a routing decision within the state’s authority. The filings also contend that private parties such as Enbridge cannot bring a federal lawsuit to enforce the treaty with Canada.

The Trump administration’s stance largely mirrors Enbridge’s position, emphasizing a national interest in preventing a disruption to the energy supply. Enbridge has stressed that treaty provisions prevent states and courts from unilaterally shutting down the pipeline. In response to the administration’s filing, Enbridge spokesperson Michael Barnes reiterated that the company believes the treaty protects it from unilateral action by states or judges.

A hearing on Enbridge’s motion for summary judgment is scheduled for Nov. 12 before U.S. District Judge Robert Jonker. The case has become a flashpoint in how far states can go in regulating cross-border energy infrastructure when federal authorities assert a broader national-security posture. Whitmer has navigated a delicate political path, occasionally acknowledging Trump’s clout while trying to shield Michigan’s interests. The two have met three times since January, including a meeting in which Trump called her a “very good person.”

Enbridge has proposed encasing the Straits segment in a protective concrete tunnel, a project estimated to cost at least $500 million. The plan would eliminate the risk of another anchor strike and rupture, according to the U.S. Army Corps of Engineers. Michigan regulators approved permits for the tunnel in December 2023, and the Corps fast-tracked the permit in April after the Trump administration identified the tunnel as a priority for expedited emergency permitting. Environmental groups and Native American tribes have challenged the Michigan Public Service Commission’s decisions on the tunnel, arguing that the panel did not adequately weigh the overall need for the pipeline when evaluating the permits. In parallel, the Michigan Supreme Court said it would hear the case, and Nessel filed her own lawsuit in 2019 seeking to void the Straits easement. The U.S. Supreme Court is weighing whether the Line 5 dispute belongs in federal or state court.

The Line 5 controversy extends beyond Michigan. In Wisconsin, a parallel dispute centers on a different stretch of Line 5 that crosses Bad River Band of Lake Superior lands. A federal judge in Madison last year ordered Enbridge to shut down the segment crossing the reservation within three years while it pursues rerouting around the land. Enbridge has appealed that order to the Seventh Circuit, and environmental groups and the Bad River Band are seeking to void state permits for the reroute. Hearings in that matter are expected to stretch into October, underscoring how multiple legal tracks are converging on a single, long-running energy project.

The overlapping lawsuits, regulatory actions, and political maneuverings have kept Line 5 at the center of debates about energy security, environmental protection, treaty obligations, and state versus federal authority. Supporters argue that the pipeline provides a reliable energy link between the United States and Canada and that the federal government must preserve that flow. Critics warn that aging infrastructure and a potential spill make the line a liability that warrants removal or a safeguarded rerouting. As the legal battles proceed, observers will watch for how the different tracks interact, whether the federal government’s foreign-policy framing sways court decisions, and how quickly a resolution might be reached that balances energy needs with environmental and tribal concerns.