Enbridge is embroiled in a protracted legal battle over its Line 5 pipeline, with state and federal courts contesting its right to operate a 4.5‑mile section beneath the Straits of Mackinac. The pipeline has been transporting crude and natural gas since 1953 and currently transports 540,000 bpd of crude and refined products from Superior, Wisconsin, to Sarnia, Ontario. The dispute sits amid growing scrutiny of aging pipelines in the Great Lakes region, where environmental groups and tribal nations argue that aging infrastructure poses a spill risk to freshwater resources. Experts first raised the concern in 2017, after Enbridge engineers admitted that they had been aware of the gaps in the section’s protective coating since 2014. A boat anchor further damaged the section in 2018, increasing concerns around a potential spill. In April, the United States Supreme Court sided with Michigan that a ruling over a section of an ageing pipeline beneath a Great Lakes channel must stay in state court. Justice Sonia Sotomayor wrote on behalf of a unanimous court that while the Calgary-based energy firm Enbridge was permitted 30 days to attempt to move the case to federal court, the company instead waited 887 days to do so, and only after it had seen developments in related litigation over the Line 5 pipeline. Michigan’s attorney general, Dana Nessel, sued in state court to void the easement that permits Enbridge to operate the pipeline. In a statement, Nessel said the ruling "makes emphatically clear that our lawsuit against Enbridge belongs before the state court, where we've argued since 2019 that Line 5 does not have a legal right to the Straits bottomlands." Nessel has previously called the section of pipeline "a ticking time bomb in the heart of the Great Lakes." State officials have also argued that Enbridge has violated state laws, including the Michigan Environmental Protection Act. Separately, a lawsuit was filed in Wisconsin over the pipeline. In June 2023, a federal judge ordered that Enbridge must shut down part of Line 5 that runs across the Bad River Band of Lake Superior’s reservation within three years. Enbridge appealed the order, and in February of this year, it commenced work to reroute the line around the reservation. The Bad River Band and environmental groups have since filed a lawsuit to halt work on the project over environmental concerns. The ongoing legal battle has raised broader questions over how much power states hold in exerting control over the fossil fuel industry. The dispute has also put pressure on United States-Canada energy relations. In addition, the battle over the pipeline has scrambled traditional political alliances due to the large number of jobs connected with pipeline operations, as well as the industry it brings to the region. After battling the issue for several years, neither Enbridge nor state lawmakers are backing down in the pipeline case, suggesting that it could take more time to resolve. In the meantime, Enbridge has been unable to progress on its project to encase the section of pipeline in Michigan, while the pipeline continues to pose a potential threat to the environment.