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...