The Canadian company argued that a 2019 lawsuit filed in a state court by Attorney General Dana Nessel should be heard by U.S. District Judge Janet Neff, who last month retained jurisdiction over a separate case initiated by the state of Michigan to halt the flow of oil through Enbridge’s Line 5.

“We are hopeful that the attorney general will agree that it makes sense for her case and the Enbridge case to be decided by the federal court rather than risk duplicative litigation and inconsistent results,” spokesman Ryan Duffy said.

But Nessel said the “outrageous maneuver” violates a federal rule that moving cases from one court to another must be done within 30 days of the initial filing.

“We will address this flagrant attempt to undermine that process in court and remain fervently committed to our belief that the fate of Michigan’s greatest natural resources should be determined in a Michigan court,” Nessel said.

Enbridge’s gambit was the latest twist in a multi-year political and legal battle over Line 5, which carries about 23 million gallons (87 million liters) daily of crude oil and natural gas liquids between Superior, Wisconsin, and Sarnia, Ontario.

It passes through northern Wisconsin and Michigan’s Upper Peninsula and is part of an Enbridge network transporting Canadian crude to refineries in both nations.

A 4-mile (6.4-kilometer) section is divided into two pipes that cross the bottom of the Straits of Mackinac, where Lake Michigan and Lake Huron meet. Environmental groups and Indigenous tribes contend they risk a spill that could pollute hundreds of miles of water and shorelines, while Enbridge says they’ve never leaked and are in sound condition.

Michigan Gov. Gretchen Whitmer ordered Enbridge in November 2020 to close the 68-year-old line, revoking a 1953 state easement allowing its placement in the straits. The company, based in Calgary, Alberta, filed a federal lawsuit and ignored the Democratic governor’s May 12 shutdown deadline.

Nessel, who had sued in state court to enforce Whitmer’s order, urged Neff to return the case to state court. But the judge ruled last month that it was “properly in federal court” because it raises issues “under consideration at the highest levels of this country’s government.”

They include Canada’s invocation of a 1977 treaty with the U.S. involving oil shipments between the two nations and federal pipeline safety regulation, Neff said.

Whitmer and Nessel responded this month by dropping their 2020 lawsuit and refocusing attention on the 2019 case filed in Michigan’s Ingham County. It argues that Line 5′s presence in the straits violates the public trust and state environmental law.