Enbridge Inc. has vowed “a thorough response through the legal process” against a new lawsuit by the Michigan government’s Democrat executive branch that seeks to revoke the state easement for its Line 5 oil conduit across the Straits of Mackinac.

In Alberta, source of most of the oil that Enbridge delivers, Energy Minister Sonya Savage added, “Like so many regulatory matters concerning pipelines, it is expected that the latest move will be headed to a long, protracted process in the American court system.”

Michigan Governor Gretchen Whitmer said in a statement, “Enbridge has imposed on the people of Michigan an unacceptable risk of a catastrophic oil spill in the Great Lakes that could devastate our economy and way of life.”

As Whitmer sent a 180-day easement revocation notice to Enbridge on Friday, Michigan Attorney General Dana Nessel filed suit to enforce eviction of Line 5 with a statement saying it “poses a great risk to our state, and it must be removed from our public waterways.”

Whitmer said an investigation by the Michigan Department of Natural Resources (DNR) showed the company “repeatedly violated the terms of the 1953 easement by ignoring structural problems that put our Great Lakes and our families at risk.”

Enbridge predicted the lawsuit would require disclosure and fair review of a report that DNR did in private with no consultations on the 67-year record of the 540,000 b/d Line 5. “The DNR rejected Enbridge’s offer to allow technical experts to discuss any questions or clarifications,” said the company.

“Line 5 remains safe, as envisioned by the 1953 easement, and as recently validated by our federal safety regulator,” said Enbridge vice-president Vern Yu.

The United States Pipeline and Hazardous Materials Safety Administration (PHMSA) let Enbridge fully refill twin-pipe Line 5 on the Straits of Mackinac floor in September after an 11-week inspection triggered by damage to an underwater support.

The PHMSA inquiry was an episode of a regulatory and court campaign that Whitmer and Nessel started soon after they won office on a 2018 platform that pledged to eliminate Line 5 as a pollution menace.

Whitmer and Nessel lost a battle in the Michigan Court of Appeals, which rejected their claim that the state constitution was violated by an Enbridge deal with the previous Republican executive branch on tucking away Line 5 in a $500 million tunnel.

A verdict is still awaited from Ingham County Court in Lansing on an earlier lawsuit that the executive branch launched using a different legal formula to try canceling the 1953 state Line 5 easement.

Raymond James analysts Chris Cox, Justin Jenkins and J.R. Weston said they saw little evidence that Enbridge’s legal success record would change, but noted that Democrat-appointed judges become a majority on the Michigan Supreme Court as of January.

Parallel to the court cases, Enbridge is in a prolonged Line 5 regulatory proceeding. The Michigan Public Service Commission (MPSC) is holding a tunnel project review on a schedule that stretches out contested hearing dates until late May 2021.