The U.S. Supreme Court on Wednesday delivered a unanimous decision in favor of Michigan Attorney General Dana Nessel, affirming that her lawsuit to shut down a section of Enbridge’s Line 5 pipeline will remain in state court.
The ruling, authored by Justice Sonia Sotomayor, determined that Enbridge waited too long to attempt moving the case to federal court, thus upholding the state’s jurisdiction over the dispute concerning the 4.5-mile segment of pipeline running beneath the Straits of Mackinac.
This section of Line 5, which has transported crude oil and natural gas liquids between Superior, Wisconsin, and Sarnia, Ontario since 1953, has been the focus of environmental and legal scrutiny for years due to concerns about potential ruptures and oil spills in the sensitive Great Lakes ecosystem.
The case originated in June 2019 when Nessel filed suit in Ingham County Circuit Court seeking to void the easement that permits Enbridge to operate the underwater pipeline segment. In June 2020, Ingham County Judge James Jamo issued a restraining order halting operations, though Enbridge was later permitted to resume after meeting specific safety requirements set by the court.
Enbridge subsequently moved the case to federal court in 2021, arguing that the dispute implicated interstate and international commerce between the U.S. And Canada. However, a three-judge panel of the 6th U.S. Circuit Court of Appeals ruled in June 2024 that the company had failed to meet a 30-day deadline for jurisdictional transfer, sending the case back to Judge Jamo’s court.
The Supreme Court’s decision on April 22, 2026, confirmed that procedural timing barred Enbridge from shifting the venue, effectively keeping the litigation in Michigan’s state judicial system where Nessel originally filed the action.
Environmental groups and tribal nations have long opposed the continued operation of Line 5 under the Straits of Mackinac, citing the risk of anchor strikes or corrosion-induced failures. Enbridge engineers disclosed in 2017 that they had known about gaps in the pipeline’s protective coating since 2014, and a boat anchor strike in 2018 caused visible damage to the structure, intensifying calls for its shutdown.
In response to these concerns, the Michigan Department of Natural Resources, under Governor Gretchen Whitmer, revoked the easement for the Straits crossing in 2020. Enbridge challenged that revocation in a separate federal lawsuit, where a judge initially blocked the state’s action; Whitmer has since appealed that ruling to the 6th Circuit Court of Appeals.
The Line 5 pipeline remains operational pending the outcome of Nessel’s easement challenge, though its future is increasingly uncertain amid ongoing legal proceedings and growing pressure to decommission aging infrastructure in the Great Lakes region.
The Supreme Court’s ruling does not address the merits of whether the pipeline should be shut down, but rather settles the procedural question of where the case should be heard—a victory for state attorneys general seeking to enforce environmental protections within their borders.
Legal experts note that the decision reinforces the principle that defendants cannot delay jurisdictional challenges indefinitely, particularly when attempting to move cases away from state courts that may be more receptive to local environmental claims.
As the case returns to Ingham County Circuit Court, both parties will continue to litigate the core issue: whether the state possesses the authority to terminate Enbridge’s right to use the submerged lands and waters beneath the Straits of Mackinac for pipeline transportation.
The next procedural step in the case is expected to involve further hearings before Judge Jamo on the validity of the easement and the state’s legal grounds for revocation, though no specific date has been set as of this reporting.
For ongoing updates on the Line 5 litigation and related environmental regulatory proceedings in Michigan, readers may consult the official docket of the Ingham County Circuit Court or the Michigan Attorney General’s website.
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